John Dalton - Billiard Ball ModelNo imperical evidence, merely assumed to be correct through observation of the simplicity of nature.
Flaws - assumed atoms were indivisible and all identical within an element.
Extra info - Didn't allow for the existence of isotopes, the slightly differing atoms within an element.
The Atomic Model
J.J. Thomson - Blueberry Muffin ModelUsed cathode ray tubes to discover electrons, and proposed that the atom was a positive substance interspersed with negative electrons.
Major flaw - Didn't account for the atomic nucleus.
Extra info - Has a unit named after him - The "Thomson", a mass to charge ratio used in mass spectrometery.
Ernest Rutherford - Rutherford ModelShot alpha particles at a gold foil expecting them to all make it through, but some were deflected. He then proposed that an atom must have a center containing most of the atom's mass.
Major flaw - Didn't account for electrostatic attratcion between electrons and the nucleus.
Extra info - Also has a unit named after him, the "Rutherford", an obsolete unit of radiatioactivity.
Planetary/Nuclear Model - Hantaro Nagaoka/Ernest Rutherford/Niel BohrNagaoka took Rutherfords model and proposed that the electrons had flat circular orbits, like saturn's rings. Bohr then took this model and simply tilted the orbits to give it the classic look we know today.
Major flaw - Couldn't explain why electrons didn't produce EMR, lose energy, and fall into the nucleus.
Extra info - Hantaro Nagaoka was probably secretly an alchemist, as he managed to produce gold and platinum from mercury (probably through nuclear reactions) in 1924.
Bohr Quantum Model - Niels BohrBohr took his existing model and added a little quantum theory to it. He explained why atoms had specific spectral lines instead of producing smears that would be produced by an electron spiraling into the nucleus, by proposing energy levels at which electrons orbited.
Major flaw - Didn't fully explain the quantum level physics of an atom, sub-energy levels, or valence shells.
Extra info - On a flight to Britain in a bomber plane, running from Nazis, Bohr passed out from oxygen starvation.