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400
Greek Model 400BC Greek Philosopher Democritus
His theory was that matter could not be devided into smaller pieces forever, eventualy the pieces would become so small that they could not be devided any more and would become invisible. Democritus named this matter 'Atomos' which means 'not to be cut'. He also believed that Atoms were small, hard particles made of the same material but were different shapes and sizes. -
Period: 400 to
Atoms Theory Timeline
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450
Aristotle's Thoery
Democritus's theory was ignored for nearly 2000 years becuase of a man named Aristotle who was a philospher at that time. His theory indicated that everything was made up from either one or all of the following elements, earth, fire, air and water. Even though this theory was inncorrect it was beleived by so many to be true becuase of his occupation of being a philosopher. -
John Dalton's Model
Dalton lead a number of experiments that finally lead to the acceptance and idea of Atoms. He found that all elements are made from invisible and indestructible particles called atoms. John also found that Atoms of the element are exactly the smae but Atoms from a different elements will be different. This theory then become the foundation of modern chemistry. -
J.J Thomson's Model
J.J Thomson was the first person to sujest that an Atom was made up from even smaller particles. He is very well known for his plum pudding theory. Atoms are constructed from positively charged substances with negativily charged electrons scattered around within similar to a pudding with raisins inside it. -
Ernest Rutherford's Model
Rutherford's experiment consisted of firing a stream of tiny positivily charged particles at a thin sheet of gold foil. A majority of the bullets passed through but some of them bounced away. This means that Atoms are made up from smaller and different particles. -
Niels Bohr's Model
During Niels experiment he placed each electron in a specific energy leval. According to his findings the electrons revolve around the nucleus. -
Modern Wave Model
Today's Atomic model is constructed around the Wave Mechanics.
