Bio1151b Chapter 2 The Chemical Context of Life
  1. Matter consists of chemical           in pure form and in combinations called            .
  2. Four elements make up 96% of living matter:         (C),           (H),         (O), and           (N).
  3. Each element is made of a single kind of       . An atom is made of           ,          , and            .
  4. The         number of an element is the number of          in the nucleus. The       number is the sum of protons plus neutrons.
  5. Electrons occupy different         with different energy         . The outermost, or          , shell contains          electrons.
  6. A           bond is the          of a pair of          electrons between different atoms of a           . These bonds are strong and stable.
  7. A         covalent bond is the sharing of two pairs of valence electrons.
  8. Electronegativity is the attraction of an atom for            . In a        covalent bond the atoms have different electronegativities and share the electrons            .
  9. In an        bond one atom strips            away from other atoms, creating          atoms called       .
  10. Ionic compounds are often called        , which may form           .
  11. Electronegativity can result in weak chemical bonds.
    • A           bond forms from the attraction of charged regions of        molecules.
    •                interactions form when transiently charged regions of molecules attract each other.
Bio1151b Chapter 3 Water and the Fitness of the Environment
  1.        is the biological medium here on Earth.
  2. Water is a        molecule, and its numerous           bonds result in unique properties.
    • Weak bonding of water molecules to each other leads to high           among water molecules. Cohesion at the liquid surface leads to high          tension.
    • Van der Waals forces between water and other molecules lead to strong           , which can be seen in the meniscus in tubes, and in            action in small tubes.
    • Water has high           heat, and moderates nearby      and ground temperatures.
    • Its high heat of               leads to              cooling of wet surfaces.
    • Solid water is less        than liquid water and floats, allowing life under frozen surfaces.
    • Water is a versatile          and can dissolve polar and ionic (hydrophilic) substances.
    • Hydrophilic substances too large to dissolve in water can form a          , a stable suspension of fine particles in a liquid, such as in the          of a cell.
  3. Water can dissociate into H+ (hydrogen) and OH- (hydroxide)       .
    • The concentration of these ions is measured on the     scale.
    • An       has a high concentration of H+ ions, while a       has a low concentration.
    •          such as carbonic acid minimize changes in pH and consist of an            pair that reversibly combines with hydrogen ions.
    •       precipitation is caused primarily by the mixing of water vapor and         and           oxides produced by the combustion of         fuels.