Chapter 2. The Chemical Context of Life 2005-2006
Why are we studying chemistry? <ul><li>Biology has chemistry at its foundation </li></ul>2005-2006
<ul><li>Everything is made of matter </li></ul><ul><li>Matter is made of atoms </li></ul><ul><li>Atoms are made of: </li><...
The World of Elements 2005-2006
Models of atoms 2005-2006 (c)
Atomic structure determines behavior <ul><li>The number of protons in an atom determines the element </li></ul><ul><ul><li...
Discussion Questions <ul><li>What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons?  </li><...
Life requires ~25 chemical elements <ul><li>About 25 elements are essential for life </li></ul><ul><ul><li>Four elements m...
2005-2006
Isotopes <ul><li>Different number of neutrons (heavier) </li></ul><ul><li>Some are unstable </li></ul><ul><ul><li>nuclear ...
Discussion Question <ul><li>Which drawing depicts the electron configuration of neon (  20 10 Ne)? </li></ul>2005-2006
<ul><li>The most common form of calcium has 20 protons, 20 neutrons, and 20 electrons. Which of the following elements wou...
<ul><li>Effect of electrons </li></ul><ul><ul><li>chemical behavior of an atom depends on its electron arrangement </li></...
<ul><li>Effect of electrons </li></ul><ul><ul><li>chemical behavior of an atom depends on number of electrons in its outer...
Elements & their valence shells 2005-2006 <ul><li>Elements in the same  row  have  the same  number of shells </li></ul>
Discussion  Question 2005-2006 Atomic chlorine has an atomic number of 17. It has _____ electrons in its third shell.
Elements & their valence shells 2005-2006 <ul><li>Elements in the same  column  have the  same valence  & similar chemical...
Discussion Question 2005-2006 Based on electron configuration, which of these elements would exhibit chemical behavior mos...
Elements & their valence shells 2005-2006 <ul><li>Moving from left to right, each element has a sequential addition of ele...
Chemical reactivity <ul><li>Atoms tend to </li></ul><ul><ul><li>Complete a partially filled outer (valence) electron shell...
Ionic bonds 2005-2006
Ionic bonds <ul><li>Transfer of an electron </li></ul><ul><li>Forms + & - ions  </li></ul><ul><ul><li>+  =   cation </li><...
<ul><li>Copper has an atomic number of 29 and a mass number of 64. What would result if an uncharged copper atom lost two ...
Covalent bonds <ul><li>Two atoms need an electron </li></ul><ul><li>Share a pair of electrons </li></ul><ul><li>Strong  bo...
Double covalent bonds <ul><li>Two atoms can share more than one pair of electrons </li></ul><ul><ul><li>double bonds (2 pa...
Multiple covalent bonds <ul><li>1 atom can form covalent bonds with two or more other atoms </li></ul><ul><ul><li>forms la...
Polar covalent bonds <ul><li>Pair of electrons not shared equally by 2 atoms </li></ul><ul><li>Water = O  +  H </li></ul>2...
Polar covalent bonds <ul><li>2 hydrogens in the water molecule form an angle  </li></ul><ul><li>Water molecule is  polar <...
Hydrogen bonds <ul><li>Positive H atom in  1 water molecule is attracted to negative O in another </li></ul><ul><li>Can oc...
<ul><li>What types of bonds are identified in the following illustration of a water molecule interacting with an ammonia m...
Reductionist view of biology <ul><li>Matter is made of atoms </li></ul><ul><li>Life requires ~25 chemical elements </li></...
Any Questions?? 2005-2006
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  • Domains of Study Domain of BioMolecules Domain of Cells Domain of Organisms Domain of Populations Domain of Communities
  • 02 Ch02chemistry2005 1

    1. 1. Chapter 2. The Chemical Context of Life 2005-2006
    2. 2. Why are we studying chemistry? <ul><li>Biology has chemistry at its foundation </li></ul>2005-2006
    3. 3. <ul><li>Everything is made of matter </li></ul><ul><li>Matter is made of atoms </li></ul><ul><li>Atoms are made of: </li></ul><ul><ul><li>protons + mass of 1 nucleus </li></ul></ul><ul><ul><li>neutrons 0 mass of 1 nucleus </li></ul></ul><ul><ul><li>electrons - mass <<1 orbits </li></ul></ul><ul><li>Different kinds of atoms = elements </li></ul>The Basics 2005-2006
    4. 4. The World of Elements 2005-2006
    5. 5. Models of atoms 2005-2006 (c)
    6. 6. Atomic structure determines behavior <ul><li>The number of protons in an atom determines the element </li></ul><ul><ul><li># of protons = atomic number </li></ul></ul><ul><ul><li>this also tells you # of electrons </li></ul></ul><ul><li>All atoms of an element have same chemical properties </li></ul><ul><ul><li>all behave the same </li></ul></ul><ul><ul><li>properties don’t change </li></ul></ul>2005-2006 VIDEO: Atom
    7. 7. Discussion Questions <ul><li>What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons? </li></ul><ul><li>An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have? </li></ul>2005-2006
    8. 8. Life requires ~25 chemical elements <ul><li>About 25 elements are essential for life </li></ul><ul><ul><li>Four elements make up 96% of living matter: </li></ul></ul><ul><ul><ul><li>• carbon (C) • hydrogen (H) </li></ul></ul></ul><ul><ul><ul><li>• oxygen (O) • nitrogen (N) </li></ul></ul></ul><ul><ul><li>Four elements make up most of remaining 4%: </li></ul></ul><ul><ul><ul><li>• phosphorus (P) • calcium (Ca) </li></ul></ul></ul><ul><ul><ul><li>• sulfur (S) • potassium (K) </li></ul></ul></ul>2005-2006
    9. 9. 2005-2006
    10. 10. Isotopes <ul><li>Different number of neutrons (heavier) </li></ul><ul><li>Some are unstable </li></ul><ul><ul><li>nuclear reactions / decay </li></ul></ul><ul><li>Split off neutrons &/or protons </li></ul><ul><ul><li>radioactivity </li></ul></ul><ul><li>Biological tool </li></ul><ul><li>Biological hazard </li></ul>2005-2006
    11. 11. Discussion Question <ul><li>Which drawing depicts the electron configuration of neon ( 20 10 Ne)? </li></ul>2005-2006
    12. 12. <ul><li>The most common form of calcium has 20 protons, 20 neutrons, and 20 electrons. Which of the following elements would be an isotope of calcium? </li></ul><ul><li>a. an atom with 20 protons, 21 neutrons, and 20 electrons </li></ul><ul><li>b. an atom with 21 protons, 20 neutrons, and 21 electrons </li></ul><ul><li>c. all of the above </li></ul><ul><li>d. an atom with 21 protons, 21 neutrons, and 21 electrons </li></ul><ul><li>e. an atom with 20 protons, 20 neutrons, and 18 electrons </li></ul>2005-2006
    13. 13. <ul><li>Effect of electrons </li></ul><ul><ul><li>chemical behavior of an atom depends on its electron arrangement </li></ul></ul><ul><ul><li>depends on the number of electrons in its outermost shell, the valence shell </li></ul></ul>2005-2006 Bonding properties How does this atom behave? VIDEO: Electron Arrangement
    14. 14. <ul><li>Effect of electrons </li></ul><ul><ul><li>chemical behavior of an atom depends on number of electrons in its outermost shell </li></ul></ul>2005-2006 Bonding properties How does this atom behave? How does this atom behave?
    15. 15. Elements & their valence shells 2005-2006 <ul><li>Elements in the same row have the same number of shells </li></ul>
    16. 16. Discussion Question 2005-2006 Atomic chlorine has an atomic number of 17. It has _____ electrons in its third shell.
    17. 17. Elements & their valence shells 2005-2006 <ul><li>Elements in the same column have the same valence & similar chemical properties </li></ul>
    18. 18. Discussion Question 2005-2006 Based on electron configuration, which of these elements would exhibit chemical behavior most like that of oxygen?
    19. 19. Elements & their valence shells 2005-2006 <ul><li>Moving from left to right, each element has a sequential addition of electrons (and protons) </li></ul>
    20. 20. Chemical reactivity <ul><li>Atoms tend to </li></ul><ul><ul><li>Complete a partially filled outer (valence) electron shell </li></ul></ul><ul><ul><li>or </li></ul></ul><ul><ul><li>Empty a partially filled outer (valence) electron shell </li></ul></ul><ul><ul><li>This tendency drives chemical reactions </li></ul></ul>2005-2006
    21. 21. Ionic bonds 2005-2006
    22. 22. Ionic bonds <ul><li>Transfer of an electron </li></ul><ul><li>Forms + & - ions </li></ul><ul><ul><li>+ = cation </li></ul></ul><ul><ul><li>– = anion </li></ul></ul><ul><li>Weak bond </li></ul>2005-2006 <ul><li>example: </li></ul><ul><ul><li>salt = dissolves easily in water </li></ul></ul>Movie: Ionic Bonds
    23. 23. <ul><li>Copper has an atomic number of 29 and a mass number of 64. What would result if an uncharged copper atom lost two electrons? </li></ul><ul><li>A. The atom would have a double negative charge and be an ion. </li></ul><ul><li>  </li></ul><ul><li>B. The atomic number of the atom would remain 29, the mass number would be reduced to 62, and the atom would be an anion. </li></ul><ul><li>C. The atomic number would remain 29, the mass number would increase to 66, and the atom would be a cation with a -2 charge. </li></ul><ul><li>D. The atomic number would be reduced to 27, the mass number would remain 64, and the atom would be an anion with a +2 charge. </li></ul><ul><li>E. The atomic number would remain 29, the mass number would remain 64, and the atom would be a cation with a +2 charge. </li></ul>2005-2006
    24. 24. Covalent bonds <ul><li>Two atoms need an electron </li></ul><ul><li>Share a pair of electrons </li></ul><ul><li>Strong bond </li></ul><ul><ul><li>both atoms holding onto the electrons </li></ul></ul><ul><li>Forms molecules </li></ul><ul><li>example: </li></ul><ul><ul><li>water = takes energy to separate </li></ul></ul>2005-2006 VIDEO: Covalent Bond
    25. 25. Double covalent bonds <ul><li>Two atoms can share more than one pair of electrons </li></ul><ul><ul><li>double bonds (2 pairs of electrons) </li></ul></ul><ul><ul><li>triple bonds (3 pairs of electrons) </li></ul></ul><ul><li>Very strong bonds </li></ul>2005-2006
    26. 26. Multiple covalent bonds <ul><li>1 atom can form covalent bonds with two or more other atoms </li></ul><ul><ul><li>forms larger molecules </li></ul></ul><ul><ul><li>ex. carbon </li></ul></ul>2005-2006
    27. 27. Polar covalent bonds <ul><li>Pair of electrons not shared equally by 2 atoms </li></ul><ul><li>Water = O + H </li></ul>2005-2006 <ul><ul><li>oxygen has stronger “ attraction ” for the shared electrons than hydrogen </li></ul></ul><ul><ul><li>oxygen has higher electronegativity </li></ul></ul>Video: Polar vs. Non-Polar
    28. 28. Polar covalent bonds <ul><li>2 hydrogens in the water molecule form an angle </li></ul><ul><li>Water molecule is polar </li></ul><ul><ul><li>oxygen end is – </li></ul></ul><ul><ul><li>hydrogen end is + </li></ul></ul><ul><li>Leads to many interesting properties of water…. </li></ul>2005-2006
    29. 29. Hydrogen bonds <ul><li>Positive H atom in 1 water molecule is attracted to negative O in another </li></ul><ul><li>Can occur wherever an -OH exists in a larger molecule </li></ul><ul><li>Weak bonds </li></ul>2005-2006 VIDEO: Hydrogen Bonds
    30. 30. <ul><li>What types of bonds are identified in the following illustration of a water molecule interacting with an ammonia molecule? Bonds 1 are polar covalent bonds, bond 2 is a hydrogen bond, and bonds 3 are nonpolar covalent bonds. </li></ul>2005-2006 <ul><ul><li>Bonds 1 and 3 are polar covalent bonds and bond 2 is a hydrogen bond. </li></ul></ul><ul><ul><li>Bonds 1 and 3 are polar covalent bonds and bond 2 is an ionic bond. </li></ul></ul><ul><ul><li>Bonds 1 and 3 are nonpolar covalent bonds and bond 2 is a hydrogen bond. </li></ul></ul><ul><ul><li>d)Bonds 1 and 3 are polar covalent bonds and bond 2 is a nonpolar covalent bond. </li></ul></ul><ul><ul><li>e) Bonds 1 and 3 are polar covalent bonds and bond 2 is a nonpolar covalent bond </li></ul></ul>
    31. 31. Reductionist view of biology <ul><li>Matter is made of atoms </li></ul><ul><li>Life requires ~25 chemical elements </li></ul><ul><li>Atomic structure determines behavior of an element </li></ul><ul><li>Atoms combine by chemical bonding to form molecules </li></ul><ul><li>Weak chemical bonds play important roles in chemistry of life </li></ul><ul><li>A molecule’s biological function is related to its shape </li></ul><ul><li>Chemical reactions make & break chemical bonds </li></ul>2005-2006
    32. 32. Any Questions?? 2005-2006
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