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460
Democritus
During 460BC there was a Greek philosopher named Democritus that was the first to propose atomic theory. He coined and use the term "Atomos" to describe what stuff was made from ant that every element had a different atom. However he was ridiculed for his propositions by his fellow philosophers. -
John Dalton
In 1804 A man named John Dalton found Democritus' work and was intrugued. He decided to toy around with some substances and found that certain substances always broke down into the same thins (elements) in the same proportions. He concluded through evidence that various substances were compounds of different elements with different atomic masses that could not be created, nor destroyed. -
J.J. Thompson
In 1987, long after the atom was now accepted by science, a scientist named J.J. Thompson discovered the electron. He created the "Chocolate Chip Cookie" model in which the cookie part itself is the nucleus with the proposed protons and neutrons, but there were also things outside a field of empty space that were hovering around an atom. He also discovered that electrons are what give an atom a negative charge. For this discovery he was awarded the Nobell Prize. -
Ernest Rutherford
This experiment deduced that all atoms had a very dense nucleus. -
Ernest Rutherford
In 1911, Ernest Rutherford made an amazing discovery to help us know more about the atom. He did an experiment in which he had a canon filled with alpha particles, a gold foil sheet and two phosphorus rings. He would shoot the alpha particles at the gold sheet and most would go straight through, he could tell this because the alpha particles reacted with the phosphorus rings, this deduced that most atoms are just filled with empty space . However some would find the nucleus and bounce off. -
Niels Bohr
In 1922 Niels Bohr won a No Bell prize for his studies on quantum theory and the structure of the atom. He was the first to construct a model of an atom. Before we only had the plum pudding model or the chocolate chip model, but since Rutherford experiment he knew that the atom had empty space and a dense nucleus so he included this in the model.
