ISCI 1001 Lecture 4: Sep 15, 2015
17 Sep 2015
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Half-life (t ) -> time it takes for of atoms in sample to undergo decay. H -> he -> t = 12. 3 yrs. 14c -> 15n -> t = 5730 40 yrs. A (atom) -> e + a+ (ion: positive ion called cation. A + e -> a : negative ion called anion. Ionic bonding: a + b -> a+ + b+ (associate w/ each other due to their charges, ex. Covalent bonding (electrons shared: a + a -> a a (molecules, h + h -> h2 (h h, a + b -> a b, molecules: compounds made up of atoms that are covalently bonded. Mixtures of 2 or more substances w/o chemical bonding or reacting. Air (solution of gases): 70% nitrogen (n2), 21% o2, 1% several other gases. __________________ area: in ice, bigger area; density decreases (*diagrams in lecture slide, fresh water has maximum density at 4 c, water molecules associate w/ other polar molecules.
