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200
400 B.C.
Democritus was another greek scholar that said that matter was made of tiny particles that could not be broken do wn any further -
300
350 B.C.
A philospher named Aristole believed in Empedocles theory and with that he created the atomic model -
400
A.D. 500-1600
A combination of philosopher, mystic, magician and chemists believed that metals grew like plants and that they ripen into gold. -
500
1650
Robert Boyle was an english scientist who did not believe in the four element model instead he made a new definition for the word element. What he means by element is unmitigated bodies This became the modern definition of an element. An element is a pure substance that cannot be chemically broken down into simipler substances. -
Mar 14, 600
Late 1700s
The first person to isolate oxygen scientifically was Joseph Priestley even tho he did not know that oxygen was an element. -
Mar 14, 700
1808
By the year of 1808 is was finally accepted that matter was made of elements the two models had come together. The english chemist John Dalton Published a theory on why elements differ on each other -
Mar 14, 1000
1911
Ernest Rutherford, was working at McGill University in Montreal. He designed a test to experiment Thomson's and Nagaoka's models. He tested for a type of radiation called alpha particles these particles are smaller than most atoms. A thin sheet of gold foil he predicted that the particles would pass right through the gold foil based on Thomson's raisin-bun model -
450 B.C.
Empedocles was a greek scholar who believed that there were four elements known as earth, air, fire, and water -
1800s
John Dalton's atomic model could not explain why on a dry winter day you would get a spark when you touch a metal door knob. Matter is Obviously able to develop positive and negative charges. -
1904
The atomic model was revised further by a person named J.J. Thomson. His discovery was that there is very light negative particles, called electrons. Also he did experiments with beams of much heavier postive particles also known as protons. The new model was known as the raisinbun model