Small Business Success on the Web PowerPoint Presentation

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Chapter 2: Chemistry

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom.

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)?

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c)

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K)

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K)

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave?

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave?

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction.

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy +

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill”

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy!

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration-

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration- Essential Questions Chapter 2: Section 2.3 2. Contrast properties of acids and bases. Give examples of each. Acids- Bases- 3. Explain the action of buffers.

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration- Essential Questions Chapter 2: Section 2.3 2. Contrast properties of acids and bases. Give examples of each. Acids- Bases- 3. Explain the action of buffers. Essential Questions Chapter 2: Section 2.3 4. What pH value is neutral. 5. What does the word alkaline mean?

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration- Essential Questions Chapter 2: Section 2.3 2. Contrast properties of acids and bases. Give examples of each. Acids- Bases- 3. Explain the action of buffers. Essential Questions Chapter 2: Section 2.3 4. What pH value is neutral. 5. What does the word alkaline mean? Section 6.1 Summary – pages 141-151 A solution is a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent). 2.3 Solutions Sugar molecules (solutes) in a powdered drink mix dissolve easily in water (solvent) to form a solution.

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration- Essential Questions Chapter 2: Section 2.3 2. Contrast properties of acids and bases. Give examples of each. Acids- Bases- 3. Explain the action of buffers. Essential Questions Chapter 2: Section 2.3 4. What pH value is neutral. 5. What does the word alkaline mean? Section 6.1 Summary – pages 141-151 A solution is a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent). 2.3 Solutions Sugar molecules (solutes) in a powdered drink mix dissolve easily in water (solvent) to form a solution. Section 6.1 Summary – pages 141-151 Chemical reactions can occur only when conditions are right. Solutions A chemical reaction (dissolving sugar in tea) may depend on: - energy availability (stir solution) - temperature (higher = faster) (heat solution) - concentration of a substance (small amount dissolves faster) - pH of the surrounding environment

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration- Essential Questions Chapter 2: Section 2.3 2. Contrast properties of acids and bases. Give examples of each. Acids- Bases- 3. Explain the action of buffers. Essential Questions Chapter 2: Section 2.3 4. What pH value is neutral. 5. What does the word alkaline mean? Section 6.1 Summary – pages 141-151 A solution is a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent). 2.3 Solutions Sugar molecules (solutes) in a powdered drink mix dissolve easily in water (solvent) to form a solution. Section 6.1 Summary – pages 141-151 Chemical reactions can occur only when conditions are right. Solutions A chemical reaction (dissolving sugar in tea) may depend on: - energy availability (stir solution) - temperature (higher = faster) (heat solution) - concentration of a substance (small amount dissolves faster) - pH of the surrounding environment Water forms ions Hydrogen ion (H+) splits off from water to leave a hydroxide ion (-OH) (dissociation) H20 ----> H+ + -OH If concentration of 2 ions is equal, water is neutral If [H+] > [-OH], water is acidic If [-OH] > [H+], water is basic pH scale = how acidic or basic a solution is

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration- Essential Questions Chapter 2: Section 2.3 2. Contrast properties of acids and bases. Give examples of each. Acids- Bases- 3. Explain the action of buffers. Essential Questions Chapter 2: Section 2.3 4. What pH value is neutral. 5. What does the word alkaline mean? Section 6.1 Summary – pages 141-151 A solution is a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent). 2.3 Solutions Sugar molecules (solutes) in a powdered drink mix dissolve easily in water (solvent) to form a solution. Section 6.1 Summary – pages 141-151 Chemical reactions can occur only when conditions are right. Solutions A chemical reaction (dissolving sugar in tea) may depend on: - energy availability (stir solution) - temperature (higher = faster) (heat solution) - concentration of a substance (small amount dissolves faster) - pH of the surrounding environment Water forms ions Hydrogen ion (H+) splits off from water to leave a hydroxide ion (-OH) (dissociation) H20 ----> H+ + -OH If concentration of 2 ions is equal, water is neutral If [H+] > [-OH], water is acidic If [-OH] > [H+], water is basic pH scale = how acidic or basic a solution is pH Scale In neutral solution [H+] = 10-7  pH = 7 Values for pH decline as [H+] increase Acids adding acid increases [H+] Bases adding base increases [OH-]

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration- Essential Questions Chapter 2: Section 2.3 2. Contrast properties of acids and bases. Give examples of each. Acids- Bases- 3. Explain the action of buffers. Essential Questions Chapter 2: Section 2.3 4. What pH value is neutral. 5. What does the word alkaline mean? Section 6.1 Summary – pages 141-151 A solution is a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent). 2.3 Solutions Sugar molecules (solutes) in a powdered drink mix dissolve easily in water (solvent) to form a solution. Section 6.1 Summary – pages 141-151 Chemical reactions can occur only when conditions are right. Solutions A chemical reaction (dissolving sugar in tea) may depend on: - energy availability (stir solution) - temperature (higher = faster) (heat solution) - concentration of a substance (small amount dissolves faster) - pH of the surrounding environment Water forms ions Hydrogen ion (H+) splits off from water to leave a hydroxide ion (-OH) (dissociation) H20 ----> H+ + -OH If concentration of 2 ions is equal, water is neutral If [H+] > [-OH], water is acidic If [-OH] > [H+], water is basic pH scale = how acidic or basic a solution is pH Scale In neutral solution [H+] = 10-7  pH = 7 Values for pH decline as [H+] increase Acids adding acid increases [H+] Bases adding base increases [OH-] pH & Biology pH of a neutral solution = 7 Acidic solutions = pH < 7 Basic solutions = pH > 7 Most biological fluids have pH 6 – 8 pH values in human stomach can reach 2 Each pH unit represents a 10-fold difference in H+ & OH- concentrations. small change in pH actually indicates a substantial change in [H+] & [OH-]

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration- Essential Questions Chapter 2: Section 2.3 2. Contrast properties of acids and bases. Give examples of each. Acids- Bases- 3. Explain the action of buffers. Essential Questions Chapter 2: Section 2.3 4. What pH value is neutral. 5. What does the word alkaline mean? Section 6.1 Summary – pages 141-151 A solution is a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent). 2.3 Solutions Sugar molecules (solutes) in a powdered drink mix dissolve easily in water (solvent) to form a solution. Section 6.1 Summary – pages 141-151 Chemical reactions can occur only when conditions are right. Solutions A chemical reaction (dissolving sugar in tea) may depend on: - energy availability (stir solution) - temperature (higher = faster) (heat solution) - concentration of a substance (small amount dissolves faster) - pH of the surrounding environment Water forms ions Hydrogen ion (H+) splits off from water to leave a hydroxide ion (-OH) (dissociation) H20 ----> H+ + -OH If concentration of 2 ions is equal, water is neutral If [H+] > [-OH], water is acidic If [-OH] > [H+], water is basic pH scale = how acidic or basic a solution is pH Scale In neutral solution [H+] = 10-7  pH = 7 Values for pH decline as [H+] increase Acids adding acid increases [H+] Bases adding base increases [OH-] pH & Biology pH of a neutral solution = 7 Acidic solutions = pH < 7 Basic solutions = pH > 7 Most biological fluids have pH 6 – 8 pH values in human stomach can reach 2 Each pH unit represents a 10-fold difference in H+ & OH- concentrations. small change in pH actually indicates a substantial change in [H+] & [OH-] Organisms contain substances called buffers to maintain their pH at the correct levels Ex. Antacids buffer the gastric juices in our stomach by raising the pH to reduce acidity Gastric ulcer Acids and bases

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Chapter 2: Chemistry Essential Questions Chapter 2: Section 2.1 1. Draw a model of the structure of a Fluorine atom. 2. Explain what determines the stability of an atom. Essential Questions Chapter 2: Section 2.1 3. Contrast ionic and covalent bonds. 4. Why is helium used to inflate airships instead of hydrogen (Hindenburg)? 2.1 Why are we studying chemistry? Biology has chemistry at its foundation Everything is made of matter Matter is made of atoms Atoms are made of: protons + charge location-nucleus neutrons 0 charge location-nucleus electrons - charge location-energy Levels (orbits) Different kinds of atoms = elements The Basics The World of Elements Models of atoms (c) Atomic structure determines behavior The number of protons in an atom determines the element # of protons = atomic number this also tells you # of electrons All atoms of an element have same chemical properties all behave the same properties don’t change Life requires ~25 chemical elements About 25 elements are essential for life Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) Four elements make up most of remaining 4%: • phosphorus (P) • calcium (Ca) • sulfur (S) • potassium (K) Bonding properties Effect of electrons chemical behavior of an atom depends on its electron arrangement depends on the number of electrons in its outermost shell, the valence shell How does this atom behave? Bonding properties Effect of electrons chemical behavior of an atom depends on number of electrons in its outermost shell How does this atom behave? How does this atom behave? Chemical reactivity Atoms tend to Complete a partially filled outer (valence) electron shell or Empty a partially filled outer (valence) electron shell This tendency drives chemical reactions Ionic bonds Complete Empty Ionic bonds Transfer of an electron Forms + & - ions Weak bond example: salt = dissolves easily in water Covalent bonds Two atoms need an electron Share a pair of electrons Strong bond both atoms holding onto the electrons Forms molecules example: water = takes energy to separate Double covalent bonds Two atoms can share more than one pair of electrons double bonds (2 pairs of electrons) triple bonds (3 pairs of electrons) Very strong bonds Multiple covalent bonds 1 atom can form covalent bonds with two or more other atoms forms larger molecules ex. carbon Essential Questions Chapter 2: Section 2.2 1. State the difference between endergonic and exergonic reactions. 2. Explain how a catalyst (enzyme) affects a chemical reaction. 2.2 Flow of energy through life Life is built on chemical reactions Chemical reactions of life Metabolism forming bonds between molecules dehydration synthesis breaking bonds between molecules hydrolysis Examples dehydration synthesis hydrolysis + H2O + H2O Examples dehydration synthesis hydrolysis Chemical reactions & energy Some chemical reactions release energy exergonic digesting food hydrolysis Some chemical reactions require input of energy endergonic building new compounds dehydration synthesis digesting molecules= less organization=lower energy state building molecules= more organization=higher energy state Endergonic vs. exergonic reactions exergonic endergonic energy released energy invested Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + Spontaneous reactions? If reactions are “downhill”, why don’t they just happen spontaneously? because covalent bonds are stable Why don’t polymers (carbohydrates, proteins & fats) just spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO2 + H2O + heat Activation energy the amount of energy needed to destabilize the bonds of a molecule moves the reaction over an “energy hill” Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheew… that takes a lot less energy! Catalysts So what’s a cell to do to reduce activation energy? get help! … chemical help… Call in the...ENZYMES! ENZYMES Essential Questions Chapter 2: Section 2.3 1. Define: Solution- Solute- Solvent- Concentration- Essential Questions Chapter 2: Section 2.3 2. Contrast properties of acids and bases. Give examples of each. Acids- Bases- 3. Explain the action of buffers. Essential Questions Chapter 2: Section 2.3 4. What pH value is neutral. 5. What does the word alkaline mean? Section 6.1 Summary – pages 141-151 A solution is a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent). 2.3 Solutions Sugar molecules (solutes) in a powdered drink mix dissolve easily in water (solvent) to form a solution. Section 6.1 Summary – pages 141-151 Chemical reactions can occur only when conditions are right. Solutions A chemical reaction (dissolving sugar in tea) may depend on: - energy availability (stir solution) - temperature (higher = faster) (heat solution) - concentration of a substance (small amount dissolves faster) - pH of the surrounding environment Water forms ions Hydrogen ion (H+) splits off from water to leave a hydroxide ion (-OH) (dissociation) H20 ----> H+ + -OH If concentration of 2 ions is equal, water is neutral If [H+] > [-OH], water is acidic If [-OH] > [H+], water is basic pH scale = how acidic or basic a solution is pH Scale In neutral solution [H+] = 10-7  pH = 7 Values for pH decline as [H+] increase Acids adding acid increases [H+] Bases adding base increases [OH-] pH & Biology pH of a neutral solution = 7 Acidic solutions = pH < 7 Basic solutions = pH > 7 Most biological fluids have pH 6 – 8 pH values in human stomach can reach 2 Each pH unit represents a 10-fold difference in H+ & OH- concentrations. small change in pH actually indicates a substantial change in [H+] & [OH-] Organisms contain substances called buffers to maintain their pH at the correct levels Ex. Antacids buffer the gastric juices in our stomach by raising the pH to reduce acidity Gastric ulcer Acids and bases Any Questions??