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General Biology: Molecules, Water, and pH

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Terms in this set (22)

  • What are the two main categories of chemical compounds?
    Inorganic and organic compounds.
  • What characterizes organic molecules?
    Presence of carbon (C) and carbon-hydrogen (C-H) bonds forming the backbone.
  • How many covalent bonds can a carbon atom form and why?
    Four covalent bonds because carbon has four valence electrons.
  • What elements commonly bond with carbon in organic molecules?
    Hydrogen (H), oxygen (O), nitrogen (N), sulfur (S), and phosphorus (P).
  • What is a molecular formula?
    A list of the types and numbers of atoms in a molecule without showing arrangement or bonds.
  • Rules for writing molecular formulas?
    Write element symbols with subscripts for quantity; order: Carbon (C), Hydrogen (H), then others alphabetically.
  • What does a structural formula show?
    Types and numbers of atoms plus every bond represented by lines (single or double).
  • What is an abbreviated structural formula?
    A simplified structural formula omitting C-H bonds and grouping atoms in functional groups.
  • What do molecular models represent?
    3-D representations of molecules using colored spheres for atoms and rods for bonds.
  • What colors represent carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur in molecular models?
    Carbon: black, Hydrogen: white, Oxygen: red, Nitrogen: blue, Phosphorus: purple, Sulfur: yellow.
  • What is an isomer?
    Molecules with the same molecular formula but different structural arrangements.
  • Why is water essential for life?
    It has unique physical properties like polarity, cohesion, adhesion, high specific heat, and ice floats.
  • What causes water's polarity?
    Uneven sharing of electrons makes oxygen slightly negative and hydrogens slightly positive.
  • Define adhesion and cohesion in water.
    Adhesion: water clings to other substances; Cohesion: water molecules bind together.
  • What is surface tension and why is it high in water?
    Resistance to breaking the surface; high due to hydrogen bonding between water molecules.
  • What is capillary action?
    Movement of water through narrow spaces against gravity via cohesion and adhesion.
  • What is pH?
    A measure of hydrogen ion concentration indicating acidity or alkalinity on a scale from 0 to 14.
  • What pH values indicate acids, bases, and neutral solutions?
    Acids: pH < 7, Bases: pH > 7, Neutral: pH = 7.
  • What does the logarithmic pH scale mean?
    Each pH unit change represents a tenfold change in hydrogen ion concentration.
  • Why is pH regulation important in living organisms?
    Maintains proper enzyme and protein function; e.g., human blood pH is tightly regulated around 7.35-7.45.
  • What is a buffer?
    A mixture of weak acid and base that minimizes pH changes by releasing or binding H+ ions.
  • What is the function of buffers in living systems?
    To maintain relatively stable pH despite addition of acids or bases.