history of the atom timeline

Main

Democritus

440 b.c

Suggested the existence of the atom. He believed atoms were indestructable and indivisible.https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcSHzT3Afp79UQxgfB6TmO8m7fEFNQ-pl6Kqqh4b0fFatCcDuqnODg

John Dalton

1803

Pictures atoms as super small particles with no internal structure.

William Crookes

1870

He invented the crooks tube, whichas you took the gas from a tube, a glow would show up if you place a high voltage across it. He noticed that a shadow would be created if something was placed in the tube, so he thought some new sort of light was being made. He called these rays - cathode rays.https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRUWMuND4oy_IuAvf6JK_jA7CG2xyriAYZFCfeYRm8MCb6FmrU8

Eugen Goldstien

1886

Looked at a cathode ray tube and found rays traveling in the opposite direction of the cathode ray. This gave proof for the positively charged particle called a proton.https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQdyoa4S_xe2aIzh2dY6VY3SGXTORs_yMxDa7-w0VB6rtUJABIs

J.J Thompson

1897

Discovered the electron. This later leads to his "plum-pudding" model. He shows a showed electrons embedded in a sphere of positive electrical charge.https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTtPUHVKO8b-EA1CPTWymURgMJmxI4FXSvSnosqhIX4EA9DVMKI8w

Hantaro Nagaoka

1904

Developed an early but incorrect planetary model of the atom. Although this model was wrong it let to the discovery of the atoms rings.https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRpk2X6HX8lwYX5AhyAuf2ZdVEnfqZO7oDB6R8WwLY3lgM6VmnLzA

Earnest Rutherford

1911

Discovered atoms have a small dense positively charged nucleus with electrons moving around it. https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTBEmDG_khGLyz65W657juOAWxawtLVBvJ83SR4Ks70541Hg2SZ

Niels Bohr

1913

Believed the electron moved in a circular orbit at fixed distances from the nucleus.https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcThKTtigZokcsL9MCRkC1HqFNmXsxLmFfbSYZs7ZzpjVeGIGA5_Fg

Louis de broglie

1923

Louis de Broglie was known for the Pauli Exclusion Principle which says moving particles like electrons have some properties of waves.https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcS-32HFLaiexrBzUqYxG9KBhtdbBGy3oCFbOu1ahdbHl-HzSJK4

Erwin Schrodinger

1926

Developed mathematical equations to describe the motion of electrons in atoms which eventually lead to the electron cloud model.https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSXmHD5w14eILAx-HlSG662EPW9IoGwjfr2uXrEufWx-3eYIZ7G

James Chadwick

1932

pic