A

AP Bio: Unit 2 Chemistry of Life

Chemistry

  1. Name three subatomic particles, charge, and location in an atom.
    • Proton (+) in the nucleus
    • electron (-) outside of the nucleus in the electron cloud
    • neutron (no charge) in the nucleus
  2. What is an isotope?
    • they have the same number of protons and electrons but different numbers of neutrons
  3. Draw an atomic representation of MgC12
  4. Explain whether Co2 is an ionic or covalent compound. Why does this arrangement satisfy all atoms involved?
    • it is covalent because it is formed between two nonmetals. It satisfies all atoms involved because it is non-polar, meaning that the atoms share outer-shell electrons equally.
  5. Define: ionic, polar and nonpolar covalent, and hydrogen bonds.
    • ionic bond - a bond between two ions of opposite charges, which holds them together
    • covalent bond - when atoms share outer--shell electrons
    • polar covalent bond - unequal sharing of electrons between atoms of different electronegativities
    • nonpolar covalent bond - equal sharing of electrons between atoms of the same electronegativity
    • hydrogen bonds - a weak bond between two molecules when the positive and negative regions are attracted to each other
  6. Explain why water is a polar molecule. What does the polarity and shape of water have to do with its ability to form hydrogen bonds?
    • there is an unequal sharing of electrons between the atoms. There are two poles, a positive hydrogen pole and a negative oxygen pole. Water molecules are attracted to oppositely charged regions on other molecules and form hydrogen bonds.
    • Hydrogen bonds in ice are stable and spread out. In liquid water, the hydrogen bonds are constantly breaking and re-forming because of the constant moving and changing shape of liquid water.
  7. Name 5 properties of water and relate them to the structure of water
    • it is a great solvent
      • the solute’s ions are attracted to water because of their charges
    • it is neutral
      • hydrogen ions and hydroxide ions are balanced
    • has high heat capacity
      • energy from the sun transformed to hydrogen bonds in water so it doesn’t get too hot it is released at night warming area
    • has high heat of vaporization
      • heat energy from body is transformed to sweat and leaves body lowering average body temp
    • has cohesive and adhesive properties
      • water’s attraction to water and other substances, form hydrogen bonds
  8. What is pH? Which range is for acids and which for bases?
    • pH scale - used to describe whether a solution is acidic or basic; measures concentration of hydrogen ions
    • acids - 0-6
    • base - 8-14
  9. Give the pH for 1/100000 H in a solution
    • pH = 5
    1. What is a buffer and why is it important for life?
    • buffer - a mixture of molecules that acts to keep the pH of a solution close to neutral
    • they are important to all living organisms because all biochemical processes work normally only when the pH remains close to 7