Atomic Theory

Democritus Like the picture below Democritus is ancient. He discovered that matter has seed-like particles called atoms. These atoms are indivisible and so extremely small that their size can’t be diminished.

Dalton John Dalton proposed a Law of Multiple Proportions. This Law lead to the proposal of the Atomic Theory in 1803. He also developed the conception of the mole. In essence he assumed that the most simple ratios would be used in nature and came up with a formula for water of H2O.

Thompson J.J. revealed the negatively charged electron in the cathode ray tube in 1897. Today, we know him for his proposal of the model of an atom – “plum pudding”.

Millikan Millikan determined the unit charge of the electron in 1909 with the assistance of his oil drop experiment. e = 1.60 X 10-19

Rutherford Ernst Rutherford asserted the nuclear atom as the result of the gold-foil experiment in 1911. He said that all of the positive charge and all of the mass of the atom is in the center.

Chadwick He discovered the neutron in 1932. This discovery led to the discovery of fission and ultimately to the atomic bomb.

Bohr Bohr presents the atom as a small positively charged nucleus surrounded by negatively charged particles (electrons) in a circular orbit, similar to our planets and the sun.

Quantum Mechanics This is a branch of physics providing a mathematical description of the wave-particle duality of matter and energy. It was developed in 1925 by Werner Heisenberg. It describes a time of revolution and mathematical structure called the wave function.

This project was done by Joshua Dickens and Curtis Hudson This project was done by Joshua Dickens and Curtis Hudson. We’d like to take this time to thank google and Christopher Green for their contribution to this Power Point. THANK YOU!!!