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Unformatted text preview: Bio 220 Elementary Chemistry Video (Campbell Chapter 2) Chemical structure Element: smallest unit that still has the same chemical properties of the substance. Cannot be broken down by chemistry (rare; they tend to react with other substances and change) Atom: smallest piece of a chemical element Charge of a normal atom is neutral Atomic Structure Nucleus (center, positively charged) Protons are positive and determine the chemical properties Protons determine the properties of the atom Neutron #s can vary (usually similar to the number of protons) o Provide nuclear stability 2 opposite charges attract, electrons and protons balance each other out 2 like charges repel, why dont protons in the nucleus cause it to explode? o Strong force in the nucleus holds these charges together o This force involves the neutrons Electrons (spin around nucleus, negatively charged) Electrons spin around in shells (1-100s of electrons) # of electrons = # of protons in nucleus The Periodic Table Hydrogen is the simplest atom (1 electron, 1 proton) 1/11 Chemistryonline lecture review of high school chem. Know basics Atoms, elements Sub-atomic structure Molecules Dont worry about: orbitals, hybridization 1/13 Unifying concepts Evolution and systematics Biological organisms are chemical systems Similar chemistry of all living organisms Energetics Reductionism Emergent Properties of Na, Cl Na is a silver metal, explosively reactive with oxygen Cl is a gas, Cl 2 is deadly poisonous 2e- + Cl 2 2 Cl-. Add Na NaCl Ion : any charged chemical. Cant predict properties of ions from knowing structure of atom Chemistry of biological systems: Bio-organic elements are only a few (make up living tissues and cells) C, H, O, N, P, S Trace elements (elements we need in very small amounts to maintain the bodys processes) Iron, Sodium, Zinc Without these people get sick Iodine is needed by the thyroid gland to create thyroxin. Lack of iodine hypothyroid (overweight, lazy). The thyroid grows uncontrollably causing a goiter Organic chemistry: deals with the chemistry of compounds containing carbon Originally molecules of natural origin, now taken to mean molecules containing C Valence : the number of bonds an element must make to be chemically stable C = 4, N = 3, O = 2, H = 1 A methane molecule (Ch4) has all four hybrid orbitals shared and has hydrogen nuclei at the corners of the tetrahedron. Elemental analysis of it has only hydrogen and carbon. Electronegativity : the ability of an atom to attract electrons Which pair of atoms has the greatest difference in electronegativity? A: O-H, or N-H Many more electrons over the Nitrogen than over the Hydrogen, therefore we see a large difference in electronegativity Polarization : Any bond in which the electrodes are distributed unequally over the atoms. : Any bond in which the electrodes are distributed unequally over the atoms....
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This note was uploaded on 03/31/2010 for the course BISC 220 taught by Professor Mcclure during the Spring '09 term at USC.
- Spring '09