-
400 BCE
Democritus
He was the first to propose an atomic universe.Democritus said that atoms were specific to the material which they composed. -
Antoine Lavoisier
Lavoisier found that mass is conserved in a chemical reaction
Lavoisier discovered the role oxygen plays in combustion. -
John Dalton
John Dalton proposed a modern theory of the atom based on the following assumptions.
1. Matter is made up of atoms that are indivisible and indestructible.
2. All atoms of an element are the same.
3. Atoms of different elements have different weights and different chemical properties.
4. Atoms of different elements combine to form compounds.
5. Atoms cannot be created or destroyed. -
J.J Thomson
discovered the electron with a cathode ray tube -
Marie Carrie
announced the discovery of two new elements, radium and polonium,also discovered radioactivity -
Max Planck
originator of the quantum theory -
Albert Einstein
First person to show a way to prove the existence of atoms using an ordinary microscope -
Robert Millikan
His oil drop experiment helped quantify the charge of an electron, which helped understand the structure of the atom and atomic theory -
Ernest Rutherford
Ernest Rutherford assumed the nuclear structure of the atom,
he discovered alpha and beta rays, and proposed the laws of radioactive decay -
Niels Bohr
Discovered that electrons travel in seperate orbits, nobel prize physics 1922. Model of the atom experiment. -
Louis De Broglie
Discovered the nature of electrons, said all matter have wave properties. 1929 nobel prize physics -
Werner Heisenberg
Stated electrons velocity and location. Nobel prize of physics 1932 -
Erwin Schrodinger
Advanced the Bohr model, predicted the location of electron. 1933 nobel prize physics -
James Chadwick
Discovered the neutron in, helped discover nuclear fission, he helped with the development of the nuclear bomb.
