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200
Democratitus 440-BC
He is the first person to discover that Items can be split down into small particles called Atoms. -
200
Aristotle 400 BC
He disagreed with Democritus, and many people believed him for a long time. -
John Dalton
He discovered that all substances are made up of atoms which can't be created, divided, or destroyed.
Atoms of the same element are exatly alike, and atoms of different elements are different.
Atoms join the other atoms to make new substances. -
Thomson
He realized that Daltons theory was wrong and that atoms had small particles in them, meaning they could be split, the particles he found out where named Electrons. His diagram was of atoms was "like plums in pudding" meaning the atom was a ball and electrons were just floating around in it. -
Rutherford
Rutherford designed a test that consisted of a beam of particles shot at a gold thin metal sheet. Most particles passed though as expected. However some of them bounced off and went into random directions, proving some of Thomson's theory. -
Rutherford
Rutherford made changes to his original theory, His changes were a new idea for the atom, making a postively charged nucleus with electrons rotating around the nucleus. He estimated that the nucleus is 100,000 smaller than the diameter of a gold atom. -
Bohr
Bohr purposed that an atom had levels for the elecctrons to use instead of randomly. He also stated that electrons are able to change paths though energy gains and loses. -
Schrodinger and Heisenberg
They discovered that Bohr was wrong and that electrons don't have a set path, instead they have a field or area where they can be found. This area is called "electron clouds"
