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200
Democratitus
He is the first person to discover that Items can be split down into small particles called atoms -
400
Aristotle 400 BC
He disagreed with Democritus, and many people believed him for a long time. -
John Dalton
by the late 1700's, scientists had learned that elements combine in certain proportions based on masss to form compounds. for example, hydrogen and oxygen always combine in the same proportion to form water. john Dalton a british chemistand schoolteacher, wanted to know why, He experimented with different substances. His results suggested that elements combine in certain proportions because they are made of single atoms. Dalton, published his atomic theory in 1803 his theory started the followin -
Thomson
He realized that Daltons theory was wrong and that atoms had small particlesin 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 made changes to his original theory, His changes were a new idea for the atom, making a postivelycharges nucleus with electrons rotating around the nucleus. He estimated that the nucleus is 100,000 times smaller then the diameter of a golt 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 dont have a set path, instead they have a field or area where they can be found. this is called "electron clouds"
