The Chemical Context of Life Matter vs. Energy-Matter: has mass and takes up space, affected by gravity, consists of elements and compounds-Energy: moves matter, potential and kinetic, ability to do work, conversions, (sound, light, heat) Elements vs. Compounds-Element: pure substance, can’t be broken down by ordinary means to another substance (ex: hydrogen (H) and nitrogen (N))-Compound: 2 or more different elements combined in a fixed ratio (ex: H2O, CO2) Elements of Life (25)-96% O, C, H, N / 4% P, S, Ca, K, and trace elements. [HINT to remember: SPONCH] Elements in the human body:Major: oxygen, carbon, hydrogen, nitrogenMinor: calcium, phosphorous, potassium, sulfur, sodium, chlorine, magnesiumTrace: boron, chromium, cobalt, copper, fluorine, iodine, iron, manganese, molybdenum, selenium, silicon, tin, vanadium, zinc Atomic Structure-atom = smallest unit of matter that retains properties of an element subatomic particles: proton (+), neutron (0), electron (-) nucleus = protons +neutrons, shell = electrons mass # = protons + neutrons atomic # = protons or electrons (never changes) isotopes = number of neutrons varies, but same number of protons radioactive isotopes used as tracers (follow molecules, medical diagnosis) (ex: carbon-12, carbon-13, carbon-14) Chemical bonds (ordered strongest to weakest)Stronger bonds…-Covalent: sharing of electrons-polar: covalent bond between atoms that differ in electron clouds. has a partial positive side and a partial negative side (ex: H2O)- nonpolar: electrons shared equally (ex: O2 or N2)-forms cells molecules-Ionic bonds: 2 ions bond (+/-), (electron donator/electron taker) -affected by their environment (eg water) (ex: NaCl) -quick reactions/responses, weaker bond, esp in waterWeaker bonds…-Hydrogen bonds: H of polar covalent molecule bonds to electronegative atom of other polar covalent molecules-Van der Waals Interactions: slight fleeting attractions between atoms and molecules close together (ex: gecko toe hairs + wall surface) all bonds affect molecule’s shape à affect molecule’s function-similar shapes = mimics (morphine, heroin, opiates mimic endorphin (euphoria, relieve pain) Chemical ReactionsReactants à Products-ex: 6CO2 +6H2O à C6H12O6 + O2-some reactions are reversible. ex: 3H2 +N2 <> 2NH3Chemical Equilibrium: point at which forward and reverse reactions offset one another exactly – reactions are still occurring but no net change in concentrations or reactants/products