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460 BCE
The idea of the Atom
Greek philosopher, Democritus, had came up with the idea of an atom. He asked many questions like, "If you keep breaking pieces in half, will it ever end? If it does end, how small is it?" Another philosopher, Aristotle, denied the idea and everyone believed him because he was very important. -
John Dalton's experiment
It would take over 2,000 years before there was an interest on atoms. Dalton did a solid sphere experiment by mixing different chemicals and to see that it's matter made of all atoms making Democritus theory true. -
Thomson- The Plum Pudding model
An English philosopher, J.J. Thomson, had created a model when he discovered electrons had a negative charge. He thought that matter needed to have a positive charge. His model ended up looking like raisins in pudding. -
Quanta
A professor of theoretical physics, Max Planck, noticed that when atoms vibrate strong enough, like heating an object until it glows, you can measure them in specific units. Planck called these Quanta. -
The Rutherford Model
Rutherford, a scientist, did an experiment with gold foil and alpha particles. The experiment showed that rays go through some gold foil, and some reflect off of it. This had proved the Plum Pudding Model wrong. -
The Bohr (planetary) Model
A danish physicist, Niels Bohr, discovered that electrons do not spiral into the nucleus. He than came up with some rules for them.
1. Electrons can orbit at only a certain allowed distances from the nucleus.
2. Atoms radiate energy when an electron jumps from a higher energy orbit. As well as absorb energy when an electron gets boosted from low energy orbit to high energy orbit. -
Erwin Schrodinger
Erwin Schrodinger, an Australian physicist, decided that he wanted to make a model of an atom as a particle wave. His theory worked like a harmonic theory except vibrations worked in circles. He then gave it a Greek symbol from the Greek lettering system. -
End of the timeline
This was created by Julia Orr from Achieve Virtual.
