CHEM LEC

• Matter is made up of chemical elements
• Elements that make up 96% of the body's mass

  • Oxygen (O)
  • Carbon (C)
  • Hydrogen (H)
  • Nitrogen (N)
• Atom


  The smallest units of matter that retain properties
• Atom


  • Consists of a nucleus that contains protons and neutrons, and electrons that move about the nucleus in electron shells
• Ion


  An atom that has a positive or negative charge
• Molecule


  A substance that consists of two or more chemically combined atoms
• Compound


  A substance that can be broken down into two or more different elements by ordinary chemical means
• Chemical bond


  Holds the atoms of a molecule together
• Valence shell


  The outermost shell of an atom where electrons that participate in chemical reactions are located
• Ionic bond


  Formed when outer shell electrons are transferred from one atom to another, forming ions with unlike charges that attract each other
• Covalent bond


  Formed when pairs of outer shell electrons are shared between two atoms
• Hydrogen bond


  A weak bond between hydrogen and certain other atoms, such as oxygen and nitrogen
• Synthesis reaction (anabolic reaction)


  Two or more atoms, ions, or molecules combine to form a new and larger molecule
• Decomposition reaction (catabolic reaction)


  A molecule is split apart into smaller molecules, ions, or atoms
• Exchange reaction


  Combination of synthesis and decomposition reactions
• Reversible reaction


  Can proceed in both directions under different conditions
• Matter is made up of substances called elements that have specific chemical and physical properties
• Chemical symbol


  Designated symbol for each element
• Atom


  • The smallest units of matter that retain properties
  • Elements are atoms of a single type having the same number of protons
  • Atoms consist of protons, neutrons, and electrons
• Covalent bond


  Two or more atoms that share electrons or make a bond
• Molecular formula


  Indicates the number and type of atoms that make up a molecule
• Ion


  An atom or molecule with a + or - charge
• Polar covalent bond


  Covalent bonds where electrons are not shared equally
• Hydrogen bond


  Formed between hydrogen atoms and oxygen or nitrogen atoms where the oxygen and nitrogen compete to bond to the hydrogen
• Metabolism


  The sum total of all the chemical reactions in a cell or organism
• Anabolic reaction


  Synthetic reactions where things are built
• Hydrolysis reaction


  Decomposition reactions where molecules are broken down
• Organic compound


  Compounds that always contain carbon, usually contain hydrogen, and always have covalent bonds
• Inorganic compound


  Structurally simple compounds that lack carbon
• pH


  Measure of the concentration of H+ in a solution
• Neutral pH


  pH of 7
• Acid


  pH less than 7, high [H+]
• Base


  pH greater than 7, low [H+]
• Buffer


  Chemical compounds that act quickly to temporarily bind or release H+ and prevent rapid, drastic changes in the pH of a body fluid
• 4 major types of organic compounds

  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic acids
• 3 principal lipids in the human body

  • Phospholipids
  • Sterols
  • Triglycerides
• Water is the most abundant substance in the body. It is an excellent solvent, participates in chemical reactions, absorbs and releases heat slowly, requires a large amount of heat to change from a liquid to a gas, and serves as a lubricant
• Inorganic acid, base, and salt

  Dissociate into ions in water
• Acid


  Ionizes into hydrogen ions (H+)
• Base


  Usually ionizes into hydroxide ions (OH-)