Biology Chapter 2

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Biology Chapter 2
2010-07-05 21:39:55

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  1. single covalent bond

    Double bond (double covalent bond)
    one pair of shared electrons (notated H-H, H:H, or H2)

    two pairs of shared electrons ...oxygen had 6 valence electrons so when two O atoms for a molecule they share two pair of electrons (notated, O=O or O2)
  2. Eloctronegativity
    The attraction of a particular kind of atom for the electrons of a covalent bond.

    The more electronegative an atom, the stronger it pulls shared electrons toward itself.
  3. Nonpolar covalent bond
    tow atoms of the same element are equally electronegative. The tug of war will result with them sharing the electrons equally. H2 or O2 are nonpolar covalent bonds
  4. polar covalent bonds
    when one atom is bonded to a more electronegative atom the electrons are not shared equally

    Water - Oxygen is very electronegative so the electrons spend more time near the nucleus of oxygen and further from the nucleus of hydrogen (this give oxygen a partial negative charge and hydrogen a partial positive charge)
  5. van der Waals interactions
    Weak bonds

    ever changing regions of negative and positive charge that enable atoms and molecules to stick to one another when they are close together
  6. chemical reactions
    making and breaking of chemical bonds that lead to changes in the composition of matter
  7. reactants
    the materials involved in a chemical reaction
  8. products
    the result of a chemical reaction
  9. equation of photosynthesis
    • 6 CO2 + 6 H2O → C6H12O6 + 6 O2
    • carbon dioxide and water result in glucose and oxygen
  10. chemical equilibrium
    when forward and reverse chemical reactions are occuring at the same rate
  11. calorie (cal)
    kilocalorie (kcal)
    amount of heat it takes to raise the temperature of 1g of water by 1°C. also the amount of heat released when 1g of water cools by 1°C

    kilocalorie - 1000 cal - the heat required to raise the temperature of 1 kg of water by 1°C
  12. specific heat
    amount of heat that must be absorbed or lost for 1g of that substance to change temperature by 1°C
  13. heat of vaporization
    quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state
  14. evaporative cooling
    as liquid evaporated the surface of the liquid that remains behind cools down. The "hottest" molecule are more likely to leave as gas, leaving behind the cooler molecules
  15. hydration shell
    the sphere of water around each dissolved ion
  16. hydrophilic
    any substance that has an affinity for water

    does not have to dissolve - cotton has an affinity for water but does not disolve