Chemistry of life is h2o chemistry, h2o most common liquid on earth, most abundant molecule in organisms, 50-50% weight of most organisms due to h2o. Life began in h2o: structure, octet rule: atoms gain/lose electrons to have full outer shell of 8 electrons name location charge. Atomic mass: mass of protons + mass of neutrons: one oxygen atom is covalently bonded to 2 h atoms, h2o molecule is neutral in charge. Since # of protons (+) equals # of electrons (-: h2o is a polar molecule, has slight negative and positive charged regions. Shared pairs e- spend more time around o nucleus than h nucleus. Ion: atom or molecule that has gained or lost 1 or more electrons. Ionic bond: attraction between 2 ions with opposite charges. Ex: nh3: large molecules having regions of negative and positive charge. Ex: sugars: water molecules exhibit cohesion and adhesion, cohesion, like molecules cling together, h2o molecules cohere due to h bonds, surface tension.