History of Atomic Theory

Democritus

404 BCE

Birth: c. 460 B.C.
Discovery: developed the concept of the ‘atom’ (indivisible) everything is made of atoms, atoms are indivisible, etc. (most of the basic knowledge we have about atoms’ properties) around 404 BC
Marriage: none
Residence: Abdera, Greece
Work: Philosopher & Mathematician
Death: c. 370 B.C.

John Dalton

1803

Birth: September 6, 1766
Given “The Queen’s Medal” for his work in science
Discovery: Atomic Theory: All matter is composed of atoms. All atoms of an element are identical. Atoms of different elements have different weights and different chemical properties. Atoms of different elements combine in simple whole numbers to form compounds. Atoms cannot be created or destroyed. When a compound decomposes, the atoms are recovered unchanged.
Lived in Manchester, England
Death: stroke on July 26,1844

J.J. Thomson

1894

Birth: December 18, 1856
Discovery: Electrons: 1894 (experimenting with cathode ray and neon gas tube experiment)
Plum Pudding Model
Marriage: Rose Paget; 1890
Residence: Cheetham Hill, England
College: Trinity College at Cambridge
1906 Nobel Prize in Physics
Cavendish Professor of Physics at the age of 28
Death: August 30, 1940

Robert Millikan

1910

Birth: March 22, 1868 (Morrison, Illinois)
Discovery: discovered elementary size and charge of an electron until 1910 when he got a more precise answer with the oil drop experiment
Professor at the University of Chicago 1910
Obtained exact value of Planck's constant 1916
Residence: the U.S.
College: Oberlin College and Columbia University
Won Nobel Prize for physics in 1923
1921 became director of Norman Bridge Laboratory of Physics at Caltech
Death: December 19, 1953 (San Marino, CA)

Ernest Rutherford

1911

Birth: August 30, 1871 (Brightwater, New Zealand)
won a Nobel Prize in 1908
Discovery: 1911, he discovered that an atom has a tiny and heavy nucleus by using his famous gold foil experiment
Residence: Cambridge, England
College: Cavendish Laboratory, University of Cambridge
Marriage: Mary Georgina Newton
Had 1 daughter
In 1919 returned to Cavendish as department chair
Death: October 19, 1937 (Cambridge, England)

Niels Bohr

1913

Birth - October 7, 1885(Copenhagen)
Discovery - 1913, ( Cavendish Laboratory, Cambridge)
Discovered and researched more thoroughly the atomic structure of the atom
Used the Quantum theory
Used Rutherford’s discovery of the atomic nucleus
“Bohr diagrams”
Death - November 18, 1962 (Copenhagen)
Won a Nobel prize for his study and discoveries of the structure of Atoms
Had 6 sons

Erwin Schrodinger

1926

Birth - August 12, 1887(Vienna, Austria)
Discovery - 1926
Created Schrodinger equation
Fundamental equation for calculating the quantization of the hydrogen atom’s energy levels
Describes how the wave function of a quantum mechanical system evolves
Used Bohr’s Atomic model
Schrodinger’s cat- Proposed a scenario of a cat in a sealed box an its fate depended on the state of a particular subatomic particle
Death - January 4,1961(Vienna, Austria) tuberculosis

James Chadwick

1932

Birth - October 20, 1891 (Cheshire, England)
Discovery -1932: proved the existence of Neutrons
Noticed odd problems with radiation and thought it had to do with Neutrons rather than the gamma ray photons of mysterious radiation
Wrote “The Possible Existence of a Neutron”
Death - July 24, 1974
had 2 daughters
Won a Nobel Prize in 1935