Atomic Theory - Timeline

Democritus discovered that everything is composed of indestructible, physically indivisible, and always moving atoms.

Neils Bohr discovered that electrons are arranged in concentric circular orbits around the nucleus.

James Chadwick discovered the neutron.

John Dalton invented the Solid Sphere Model.

J.J. Thomson created the Plum Pudding Model.

Ernest Rutherford came up with the Nuclear Model.

Neils Bohr created the Planetary Model of the atom.

Erwin Schrodinger invented the Quantum Model of the atom.

Joseph Proust discovered that a compound is composed of exact proportions of elements by mass regardless of how the compound was created.

Marie and Pierre Curie discovered that thorium also emitted radiation depended upon the element present in the compound.

Lavoiser found that mass is conserved in a chemical reaction, but the amount of hydrogen and oxygen atoms before and after the reaction is the same.

Robert Millikan experimented with the charge of electrons to prove Thomson's theory right.

Michael Faraday discovered that electrical forces were responsible for the joining of atoms in compounds.