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ch 2

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Terms in this set (23)

  • What are the three main subatomic particles of an atom?
    Protons (positive charge), Neutrons (neutral), and Electrons (negative charge).
  • Where is most of an atom's mass located?
    In the nucleus, which contains protons and neutrons.
  • What is the electron cloud in an atom?
    The region around the nucleus where electrons whirl and occupy energy levels.
  • Define atomic number and mass number.
    Atomic number is the number of protons; mass number is the total of protons and neutrons.
  • What are isotopes?
    Atoms with the same number of protons but different numbers of neutrons, having identical chemical properties but different mass numbers.
  • What determines the chemical properties of an element?
    The number of electrons in the outermost electron shell (valence shell).
  • What makes an atom reactive or inert?
    Atoms with unfilled outer shells are reactive; atoms with full outer shells (noble gases) are inert.
  • What is an ion?
    An atom that has gained or lost electrons and thus has a net electrical charge.
  • What is a cation and an anion?
    A cation is a positively charged ion (lost electrons); an anion is a negatively charged ion (gained electrons).
  • How are ionic bonds formed?
    By electrical attraction between cations and anions after transfer of electrons.
  • What is a covalent bond?
    A chemical bond formed by sharing electrons between atoms.
  • Difference between nonpolar and polar covalent bonds?
    Nonpolar bonds share electrons equally; polar bonds share electrons unequally, creating partial charges.
  • What is metabolism?
    All chemical reactions in the body that provide energy, maintain, repair, grow, and perform special functions.
  • Define kinetic and potential energy in biological context.
    Kinetic energy is energy of motion; potential energy is stored energy with capacity to do work.
  • What are reactants and products in a chemical reaction?
    Reactants are substances at the start; products are substances formed at the end of the reaction.
  • Describe decomposition and synthesis reactions.
    Decomposition breaks molecules into smaller parts; synthesis assembles smaller molecules into larger ones.
  • What is hydrolysis and dehydration synthesis?
    Hydrolysis breaks bonds by adding water; dehydration synthesis forms bonds by removing water.
  • What role do enzymes play in chemical reactions?
    Enzymes lower the activation energy required, speeding up reactions without being consumed.
  • What is activation energy?
    The minimum energy needed to start a chemical reaction.
  • List four important properties of water in the body.
    Lubrication, chemical reactant, high heat capacity, and solvent.
  • Why is water a good solvent?
    Because its polar molecules form hydration spheres that dissolve many inorganic and organic substances.
  • What are electrolytes?
    Soluble inorganic substances whose ions conduct electrical current in body fluids.
  • Define hydrophilic and hydrophobic molecules.
    Hydrophilic molecules interact readily with water; hydrophobic molecules do not.