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Democritus
Democritus proposed that if you continue to divide things that eventuly you would come up with an object that could not be divided. He called this an atom which came from the Greek word atomos which means "not able to be divided". -
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Aristotle
Aristotle disagreed with Democritus's ideas. He believed that you would never end up with a particle that could not be cut. He was believed to be right becasue he had such a strong influence. Unfortunately Democratis was right. -
Dalton
He tested why particles were only forming in certin ratios. He found out this was the case because they are made of single atoms. He published his atomic theroy in 1803. -
Thomson
He found a mistake in Dalton's theroy. He found that atoms are made up of even smaller particles which means they can be divided. He discovered electrons through an experiment with cathode-ray tube. -
Rutherford
He was one of Thomson's students that decided to test his theroy. He made an experiment to test the parts of an atom. He aimed a beam of small positively charged particles at a thin sheet of gold. Most of the particles went strait through but some bounced. He concluded that atoms are mostly empty space with a small amount of highly dense matter. -
Rutherford
He revised his atomic theroy at this point. He said that the center of an atom is a small, extremely dense, and positively charged part called a nucleus. He said that the nucleus was 100,000 times smaller then diameter of a gold atom. -
Bohr
Bohr studied the way atoms reacted with light. He proposed that electrons move around the nucleus in certain paths or energy levels. in Bohr's modle there was no paths between energy levels -
Schrodinger and Heisenberg
They further explained the nature of electrons. They stated that electrons do not move in definite paths. They also stated that there are places where electrons can be found known as electons clouds.
