The Atom

Democritus (BC)

370

BC
Found that matter is made of tiny invisible particles in different formations, and he named them atoms.

Isaac Newton

Jan 1, 1704

"Proposed" that tiny solid particles that kept moving made up the universe.

John Dalton

Jan 1, 1803

Created a theory stating that atoms were spheres with measurable properties of mass.

James Clerk Maxwell

Jan 1, 1873

Found that magnetic and electric fields filled space in the atom.

G.J. Stoney

Jan 1, 1874

Proposed that the electricity was made from, what he named, electrons.

J.J. Thomson

Jan 1, 1897

Discovered the electron by using a cathod ray tube.

Hantaro Nagaoka

Jan 1, 1903

Created the "Saturnian" model of an atom.

R. A. Millikan

Oct 19, 1909

Used the oil drop experiment to find the charge and mass of an electron.

Ernest Rutherford

Jan 1, 1911

Used the gold foil experiment to discover the almost solid, positively charged nucleus. Made the planetary model.

H. G. J. Moseley

Jan 1, 1914

He used X-ray tubes to find the charge of the nuclei of atoms, and he said that the atomic number is equal to the number of protons.

John Cockcroft / Ernest Walton

Jan 1, 1929

Produced alpha particles by building a linear accelerator that shot protons at lithium.

Erwin Schrodinger

Jan 1, 1930

Found that electrons were in a cloud and came up with an equation - wave mehcanics - to explain them.

Paul Dirac

Jan 2, 1930

Suggested that there were anti-particles in an atom, and found the pistron (first anti-electron).

James Chadwick

Jan 1, 1932

Discovered the neutron using alpha particles and came up with a model for the atom.

Neils Bohr

Jan 1, 1992

Created the Bohr model of an atom.