History of Atomic Theory

John Dalton

Sep 6, 1766

http://www.chemheritage.org/discover/online-resources/chemistry-in-history/themes/the-path-to-the-periodic-table/dalton.aspx
Discovered Atomic Weights

Niels Bohr

Oct 7, 1855

http://www.nobelprize.org/nobel_prizes/physics/laureates/1922/bohr-bio.htmlhe extended upon Rutherford's atomic theory by proposing that electrons travel only in certain successively larger orbits. He said that the outer orbits could hold more electrons than the inner ones, and that these outer orbits determine the atom's chemical properties.

J.J Thompson

Dec 18, 1856

http://www.nobelprize.org/nobel_prizes/physics/laureates/1906/thomson-bio.html
Determined the basic structure of an atom.

Ernest Rutherford

Aug 30, 1871

http://www.rutherford.org.nz/
Discovered that the atom is not the smallest unit and discovered the nucleus.

James Chadwick

Oct 20, 1891

http://www.nobelprize.org/nobel_prizes/physics/laureates/1935/chadwick-bio.html
Proved the existance of Neutrons

Democritus

Mar 2, 2022

http://plato.stanford.edu/entries/democritus/
Discovered that atoms are infinite and makeup everything.