Dates are included for a frame of reference.. Around 400 B.C. Atomos => indivisible He suggested...
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Transcript of Dates are included for a frame of reference.. Around 400 B.C. Atomos => indivisible He suggested...
History of the AtomDates are included for a frame of reference.
Democritus
Around 400 B.C. Atomos => indivisible He suggested that all substance in the
universe was made up of particles so tiny that nothing smaller was possible.
He regarded those particles as unchangeable and indestructible, and as the only content of the universe.
The “Mocker”
Dalton
1803 Atoms = small, dense, spheres Billiard Ball Model Atomic Theory
Dalton
Dalton’s Atomic Theory
Tiny particles called atoms make up all elements
Atoms of the same element are identical
Compounds are made with whole number ratios of atoms
Chemical reactions are when compounds are broken and reformed
Thomson
1897 Discovered the electron, and they
were negative Cathode Ray Tube experiment Plum pudding model
Immobile electrons
Thomson
Rutherford
1911 Gold Foil Experiment Discovered atom was mostly empty
space Discovered the nucleus
Dense, positive, small, in center Atomic Model
Rutherford
Bohr
1913 Electrons were located in shells
(fixed orbits) Electrons can move to other shells Planetary Model
Bohr
Millikan
1916 Oil-drop experiment
Mass of an electron Exact charge of an electron
Millikan’s Oil Drop Experiment
Schrödinger
1926 Electron cloud of probability Electron Cloud Model
Electron Cloud Model
Chadwick
1932 Discovered the neutron