Atomic Model

1800

350 BC

RutherfordFounded gold foil experimentAlpha particals deflect at various anglesConcluded an atom is mostly open spaceElectons hold on by positive nucleusProtons are positively charged

1920

Aristotle says "empty space doesn't exist"

Democritus says "matter consists of invisible particals

400 BC

1930

Robert Millikan comes up with the charge of an electron.

JJ ThompsonDetermines charge-mass ratioidentifies first subatomic particalPlum-Pudding Model

1900

John Dalton Matter is composed of atoms.Atoms are indivisible.

Atomic Model TIMELINE

1900s

Atomic Model now

Henry Moseleyeach element contains unique nucleinumber of proton elementdeveloped atomic number

Atoms of given elements are identical.Atoms of different elements differ.

In the 1920s, the electron cloud model was descovered, made of protons, nutrons, and electrons.

ChadwickShowed that nucleus contained nuetronsNuetrons- no charge but has mass

Videohttp://www.youtube.com/watch?feature=player_detailpage&v=QbWKF9uDF7w