Timeline of the Atom

Events

Democritus' atomic theory claims that matter is made up small indestructible units he called atoms

400 BC

Isaac Newton theorized that atoms are small, solid, and constantly moving.

1704

John Dalton claimed that atoms of the same element are all identical and that compounds were combined elements

1803

Thomson used cathode ray tubes to determine that atoms also have electrons which were negatively charged

1897

Rutherford claimed that electrons moved in orbits around atoms and the nucleus was positively charged

1898

Frederick Soddy created the term Isotope to explain the breakdown of radioactive elements

1900

Bohr proclaimed that the electrons had orbits

1922

de Broglie discovered that atoms have wave properties

1924

Shrodinger used quantum mathematics to find out where the electrons would orbit

1926

Heisenberg developed the Uncertainty Property, which claims that electrons move so fast that even if you found out where they were, they would be gone in the next second

1927

James Chadwick discovered neutrons which had masses close to the protons

1932