Chemical contextoflife[1]


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Chemical contextoflife[1]

  1. 1. Chapter 2 The Chemical Context of Life
  2. 2. Basic Terms <ul><li>Element = cannot be broken down to other substances </li></ul><ul><ul><li>Examples: Na, O, C, Cl </li></ul></ul><ul><li>Compound = combination of 2 or more different elements </li></ul><ul><ul><li>Examples: NaCl, CO 2 , CH 4 </li></ul></ul>0
  3. 3. Requirements for Life <ul><li>92 natural elements… </li></ul><ul><ul><li>25 are essential to life </li></ul></ul><ul><ul><li>Carbon, oxygen, hydrogen, and nitrogen make up 96% of living matter </li></ul></ul><ul><li>Trace elements are needed, too, though </li></ul><ul><ul><li>Iodine…lack of = goiter!! </li></ul></ul>0
  4. 4. Atomic Structure <ul><li>Atom = smallest possible amount of an electron that retains the element’s properties </li></ul><ul><li>Subatomic particles: </li></ul><ul><ul><li>Protons = + charge </li></ul></ul><ul><ul><li>Electrons = - charge </li></ul></ul><ul><ul><li>Neutrons = neutral charge </li></ul></ul>0
  5. 5. Atomic Structure <ul><li>Atomic Number: </li></ul><ul><ul><li># of protons (also equals # of electrons…) </li></ul></ul><ul><li>Mass Number: </li></ul><ul><ul><li># of protons + # of neutrons </li></ul></ul><ul><ul><ul><li>Examples </li></ul></ul></ul>0
  6. 6. Isotopes <ul><li>Def’n: atoms that have more neutrons than atoms of the same element </li></ul><ul><ul><li>Same number of protons, but different number of neutrons </li></ul></ul><ul><ul><li>Therefore…different atomic mass! </li></ul></ul>0
  7. 7. Radioactive Isotopes <ul><li>Radioactive Isotopes: </li></ul><ul><ul><li>Nucleus decomposes spontaneously, giving off particles and energy (ie. Carbon 14) </li></ul></ul><ul><li>Uses: </li></ul><ul><ul><li>Dating fossils </li></ul></ul><ul><ul><li>Tracers </li></ul></ul><ul><ul><ul><li>marking something and finding it again later </li></ul></ul></ul>
  8. 8. Energy <ul><li>Energy = the ability to do work </li></ul><ul><li>Energy levels </li></ul><ul><ul><li>Further out = more energy </li></ul></ul>
  9. 9. Electron Orbitals <ul><li>Electrons move within orbitals </li></ul><ul><ul><li>Orbitals are 3-D spaces, not linear </li></ul></ul>
  10. 10. Valence Shells <ul><li>Valence shell = outermost energy level </li></ul><ul><li>Valence shell determines an atom’s reactiveness </li></ul><ul><li>Alone = reactive/unhappy! </li></ul><ul><li>Paired = nonreactive/happy  ! </li></ul>
  11. 11. Chemical Bonding <ul><li>2 types of bonding that occurs between atoms: </li></ul><ul><ul><li>Covalent bonding </li></ul></ul><ul><ul><li>Ionic bonding </li></ul></ul>
  12. 12. Covalent Bonds <ul><li>Def’n: 2 atoms share a pair of valence electrons </li></ul><ul><li>Valence = bonding capacity </li></ul>
  13. 13. Covalent Bonds <ul><li>Nonpolar covalent bonds </li></ul><ul><ul><li>Electrons are shared equally between 2 atoms </li></ul></ul><ul><li>Polar covalent bonds </li></ul><ul><ul><li>Electrons are NOT shared equally between 2 atoms </li></ul></ul><ul><li>Whether a bond is nonpolar and polar is determined by an atom’s electronegativity </li></ul><ul><ul><li>Electronegativity = how much an atom wants to pull its electrons to itself </li></ul></ul>
  14. 14. Ionic Bonds <ul><li>Def’n: one atoms “donates” its electrons to the other </li></ul><ul><ul><li>Cation = atom that donates, + </li></ul></ul><ul><ul><li>Anion = atom that receives, - </li></ul></ul>
  15. 15. Hydrogen Bonds <ul><li>A hydrogen atom that is covalently bonded to one electronegative atom is also attracted to another electronegative atom </li></ul><ul><li>Usually between oxygen of one water molecule and hydrogen of another </li></ul><ul><li>Individually weak, but strong together! </li></ul>
  16. 16. Molecular Shape & Function <ul><li>Molecules have characteristic sizes and shapes </li></ul><ul><li>Molecular shape is crucial in biology because it determines how biological molecules recognize and respond to each other with specificity </li></ul><ul><ul><li>Examples: ?? </li></ul></ul>
  17. 17. Applications <ul><li>Morphine </li></ul><ul><ul><li>Lock and key concept </li></ul></ul><ul><ul><li>Morphine is designed to be the same shape as endorphins </li></ul></ul><ul><ul><ul><li>Therefore, morphine will bind to the endorphin binding site in the brain </li></ul></ul></ul><ul><ul><ul><li>Brain will be tricked! </li></ul></ul></ul><ul><ul><li>Heroin works in the same way </li></ul></ul>
  18. 18. Chemical Reactions <ul><li>Def’n: the making and breaking of chemical bonds </li></ul><ul><li>Reactants  Products </li></ul><ul><li>1 st Law of Thermodynamics: </li></ul><ul><ul><li>Energy can be neither created nor destroyed </li></ul></ul>