MODEL OF AN ATOM TIMELINE

Antonio Rodriguez

1803

John Dalton

Summary

John Dalton pictures atoms as as tiny, indestructible particles, with no internal structure

1897

J.J. Thomson

Summary

J. J. Thomson, a British scienist, discovers the electron, leading to his "plum pudding" model. He pictures electrons embedded in a sphere of positive electric charge

1904

Hantaro Nagaoka

Summary

Hantaro Nagaoka, a Japanese physicist, suggests that an atom has a central nucleus. Electrons move in orbits like the rings around Saturn

1911

Ernest Rutherford

Summary

Ernest Rutherford states that an atom has a dense, positively charged nucleus. Electrons move randomly in the space around the nucleus.

1913

Niels Bohr

Summary

Niels Bohr's model, the electrons move in spherical orbits at fixed distances from the nucleus

1924

Louis de Broglie

Summary

Louis de Broglie proposes that moving particles like electrons have some properties of waves. Within a few years evidence is collected to support this idea

1926

Erwin Shrodinger

Summary

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

1932

James Chadwick

Summary

James Chadwick confirms the existence of neutrons,which have no change Atomic nuclie contain neutrons and positively charged protons.