Atomic Timeline

Mia Miller

-1803: John Dalton; Model of the Atom

According to John Dalton, the atom is a tiny, indestructible particle with no internal structure.

-1897: J.J. Thomson; Model of the Atom

J.J. Thomson was a British scientist; he discovered the electrons.

-1904: Hantaro Nagaoka; Model of the Atom

Japanese physicist, Hantaro Nagaoka, suggested the atom had a central nucleus. The electrons move in orbits like the rings around Saturn.

-1911: Ernest Rutherford; Model of the Atom

Ernest Rutherford states that there is a dense, positively charged nucleus in the center of the atom. The electrons move in the available space randomly around the nucleus.

-1913: Niels Bohr; Model of the Atom

The electrons move in spherical orbit at fixed distances around the nucleus.

-1924: Louie de Broglie; Model of the Atom

Louie de Broglie proposes that moving particles like electrons have some properties of waves.

-1926: Erwin Schrödinger; Electron Cloud Model of the Atom

Erwin Schrödinger develops mathematical equations to describe the motion of electrons in atoms. His work develops the electron cloud.

-1932: James Chadwick; Model of the Atom

Chadwick confirms the existence of neutrons, which have no charge. Atomic nuclei contain neutrons and positively charged protons.