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