NSCI 1321 Study Guide - Final Guide: Electron Configuration, Noble Gas, Atomic Number
10 Sep 2015
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John newlands: arranged the elements according to atomic mass. Law of octaves: when arranged in atomic mass order, every 8th element had similar properties. Mendelev did a better job at arranging than meyer. Grouped by atomic mass and chemical and physical properties. He predicted the properties of elements not yet discovered. He arranged the 68 elements available in 1869. Henry mosely: he confirmed the idea of atomic number. Determined the correlation of frequency of x-rays generated when an element was bombarded by high energy electrons. In general, atomic mass increases as atimic number increases. For the representative elements, valence electrons are located in the highest unoccupied (n) shell. Core electrons: these are non-valence electrons located losest to the nucleus. Noble gases: the outermost shell is completely full they are very stable elements and hardly react. The configuration of an anion or cation looks like the configuration of the preceeding or following noble gas respectively.
