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460 BCE
Democritus
Democritus suggests the existence of atoms from the Greek word "Atomos," which means Indestructible. -
John Dalton
John Dalton believed that:
1. All elements are composed of tiny particles known as atoms
2. Atoms from the same element are identical
3. Atoms from a different element have different properties
4. Many things can happen to an atom during a chemical reaction, but it will never change into an atom from a different element
He developed the FIRST MODEL OF THE ATOM -
J.J Thomson
J.J Thomson DISCOVERED THE ELECTRON using an instrument called the cathode ray tube. It picked up negative energy in the air. The model Thomson used was called the "Plum Pudding" model because he said that the electrons were like plums in a positively charged "pudding" -
Ernest Rutherford
Rutherford discovered the fact that atoms have a nucleus using his Gold Foil Experiment, in which he fired alpha particles that were positively charged at a thin sheet of gold foil. Most of the particles went through the foil, a few were deflected, and a very small amount were GREATLY deflected. He had found out that the nucleus was small, the nucleus was dense, and the nucleus was positively charged. This also proved that atoms were mostly EMPTY SPACE. -
Neils Bohr
He piggy backed off of Rutherford a little, stating that electrons ORBIT THE NUCLEUS WITH DIFFERENT PATHS AND CERTAIN AMOUNTS OF ENERGY LEVELS. -
Schrodinger & Heisenberg
Schrodinger has piggy backed a little off of Bohr, in which he has stated that electrons move around the nucleus in a wavy pattern. He used the Electron cloud model. He believed we could predict the movement of an electron. IT IS CURRENTLY THE MOST WIDELY ACCEPTED MODEL OF THE ATOM.
