-
460 BCE
Democritus
Believed everything was composed of atoms too small to see -
Period: 460 BCE to
History of the Atom
-
384 BCE
Aristotle
Believed everything was made up the elements water, earth, air, and fire. However many times you cut something in half, there will always be a small piece -
Evangelista Torrecelli
Discovered what changes atmospheric pressure band created the barometer -
Antoinne Lavoisier
Found that atoms were indivisible and developed the law of conservation of mass -
John Dalton
Developed the atomic theory saying elements were made up of atoms, all atoms of the same element were identical, atoms cannot be created, destroyed, or divided, and atoms combine to create whole-number ratios of compounds -
J.J. Thomson
Discovered the electron and developed the plum pudding model of the atom using a cathode ray experiment -
Ernest Rutherford
Conducted a gold-foil experiment and discovered the proton nucleus to create his nuclear model of the atom -
Robert MIllikan
Discovered the charge and mass of the electron -
Niels Bohr
Discovered the electron orbitals and developed the planetary model -
Werner Heisenberg
Developed the theory of quantum mechanics -
Erwin Schrodinger
Discovered the behavior of the electron to be as waves -
James Chadwick
Discovered the neutron