CHEM 107 Lecture 2: Chapter 2 - Atoms, Ions, and Molecules
25 Jul 2016
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Document Summary
Law of multiple proportions: when two elements form two different compounds, masses of a and b expressed as ration of small, whole numbers (co2 = 2/1) J. j. thompson: discovered electron, beam from cathode ray tube toward positively charged plate, mass to charge ration, plum-pudding model: e- diffuse throughout positively charged sphere. Robert millikan: mass of an electron with oil-drop experiment. Henri becquerel: radioactivity and nuclear atom, passed alpha particles through gold foil, discovered working model of atom. Nucleus: positively charged center, contains majority of atom"s mass, protons and neutrons. Atomic mass units (amu: 1 amu = 1 dalton (da) Carbon: 6 protons, 6 neutrons = 12 amu. Aston"s experiment: isotopes, same number of protons but different number of neutrons. Natural abundance: proportion of particular isotope, usually expressed as percentage relative to all isotopes for that element in natural sample.
