CHEM-UA 109 Lecture Notes - Lecture 15: Bohr Model, Atomic Number, Weighted Arithmetic Mean
30 Aug 2016
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Document Summary
Chemistry: the study of the composition of matter and the changes it undergoes. All matter is made of of atoms. Thomson used cathode ray tubes to show that negatively charged particles (electrons) exist. He made the plum pudding model, in which there were negative electrons dispersed throughout a slightly positively charged atom. He shot alpha particles at thin pieces of gold foil and the results were as follows: most of the particles passed straight through, some slightly deflected, and some were strongly deflected. The fact that most particles passed straight through shows that atoms are mostly empty space. The fact that some were strongly deflected shows that atoms have a nucleus: a dense positively charged center (the particles strongly deflected hit the nuclei of the gold atoms, and positive repels positive) Developed the planetary model, where there were shells of electrons which orbit the nucleus. The electron notations on the periodic table show the bohr notation.
