History of the Atom

Democritus

400 BCE

Formation of Atomic Theory- All matter is made up of tiny invisible particles (atoms).

John Dalton

Sep 6, 1766

Introduced the atomic theory into chemistry. All matter is made up of atoms and atoms are indivisible and indestructible. Compounds are also formed by a combination of two or more different kinds of atoms

Dmitri Mendeleev

Feb 8, 1834

Created periodic table of elements and used it to correct the properties of already discovered elements and to predict properties of elements that weren't discovered yet

Eugen Goldstein

Sep 5, 1850

Credited with the discovery of the proton

JJ Thomson

Dec 18, 1856

Credited with the discovery and identification of the electron and with the discovery of the first subatomic particle

Max Planck

Apr 23, 1858

Discovered energy quanta- Quantum Theory

Robert Millikan

Mar 22, 1868

Awarded Nobel Prize in 1923 for the measurement of the elementary electric charge

Ernest Rutherford

Aug 30, 1879

First to discover that atoms have a small charged nucleus surrounded by by empty space, and are circled by tiny electrons

Niels Bohr

Oct 7, 1885

Received Nobel Prize in Physics in 1922 for making contributions to the knowledge of atomic structure and quantum theory.

Erwin Schrodinger

Aug 12, 1887

Used mathematical equations to describe the likelihood of finding an electron in a certain position- Also known as quantum mechanical model of the atom

James Chadwick

Oct 20, 1891

Discovered the neutron in 1932 and received a Nobel prize for it in 1935

Werner Heisenberg

Dec 5, 1901

Developed theory of quantum mechanics which resulted in the discovery allotropic forms of hydrogen