[Earth Sciences 2123A/B] - Midterm Exam Guide - Ultimate 17 pages long Study Guide!

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Daltons - all atoms of one elements have the same size and weight: atoms can be combined to produce new compounds. Atoms of the elements unite chemically in simple numerical ratios to form compounds: the smallest unit of matter that possesses the properties of an element. Elements a single or isolated group of particles composed only one species of atoms. Anything smaller than an atom is subatomic. When thompson discovered electrons he proposed the plum-pudding model a lot of positive charge with random negative charges: neutral atoms are made up of an equal number of positive and negative particles. Rutherford model positively charged nucleus surrounded by negatively charged electrons orbiting around it: his famous gold foil experiment showed that atoms are mostly empty space. Bohr model explained why electrons could remain in certain allowed orbits without radiating energy. Where the electrons are determining the behaviour of the atom and elements is largely controlled by the number and configuration of electrons.