BIOCHEMISTRY

• Element


  A substance that cannot be broken down into simpler chemical substances
• Atom


  Smallest particle of an element that still has the properties of that element
• Nucleus


  Center of an atom
• Subatomic particles in atomic nuclei

  • Protons
  • Neutrons

  
• Protons


  Positively charged, large in size, the number determines the identity of an element (atomic number)

  
• Neutrons


  Neutral charge, same size as protons, add mass to the nucleus

  
• Atomic number


  The number of protons in the nucleus of an atom

  
• Atomic mass


  The number of protons + the number of neutrons in the nucleus

  
• Electrons


  Negatively charged particles that orbit the nucleus in an electron cloud, very small

  
• In an atom, the number of protons=the number of electrons, atoms have no electric charge
• Electron energy levels and sublevels

  • 1st energy level holds up to 2 electrons (s sublevel)
  • 2nd energy level holds up to 8 electrons (s sublevel 2, p sublevel 6)
  • 3rd energy level holds up to 18 electrons (s sublevel 2, p sublevel 6, d sublevel 10)
  • 4th energy level holds up to 32 electrons (s sublevel 2, p sublevel 6, d sublevel 10, f sublevel 14)
• Isotopes


  Atoms of the same element that have a differing number of neutrons in their nuclei

  
• Compound


  Substance composed of two or more elements that have been combined chemically
• The properties of a compound are different than the properties of the elements that make it up
• Compound formation


  • 2H2 + O2 2H2O
• Chemical bonds


  Hold compounds together
• Types of chemical bonds

  • Covalent bonds
  • Ionic bonds
• Covalent bonds


  Form when atoms share electrons to form a compound, form molecules
• Ionic bonds


  Form when electrons are transferred from one atom to another, form ions (atoms that have gained or lost electrons)
• Ionic bonds do not form molecules
• Chemical equation


  Must obey the Law of Conservation of Matter, have reactants and products
• Chemical equations must be balanced, the number of atoms before and after the reaction must be equal
• Mixture


  Combination of substances where the individual components retain their own properties
• Types of mixtures


  • Homogeneous (uniformly mixed)
  • Heterogeneous (not uniformly mixed)
• Solution


  A mixture where one substance (the solute) is dissolved in another (the solvent)
• Water is the universal solvent
• Acid


  A substance that releases H+ ions when mixed with water, has a pH of 0-6
• Acid example


  • HCl H+ + Cl-
• Base


  A substance that releases OH- ions when mixed with water, has a pH of 8-14
• Base example


  • NaOH Na+ + OH-
• A pH of 7 is neutral, neither acid nor base
• pH scale


  Measures the concentration of H+ ions in solution, the greater the concentration the lower the pH
• The pH scale shows an exponential relationship, each number represents a factor of 10
• Acids and bases can neutralize each other, the result is a neutral solution with a pH of 7
• Indicators


  Chemicals that change color in the presence of other chemicals
• Common indicators


  • Litmus paper
  • Bromthymol blue
  • Phenolphthalein
• Water


  A polar molecule, with a negative charge on the oxygen end and positive charge on the hydrogen ends
• The polarity of water allows it to dissolve ionic and polar compounds
• Hydrogen bonds


  Weak bonds that hold many important molecules together
• Adhesion


  The tendency of water to stick to the walls of its container, responsible for capillary action