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Democritus
Proposed the matter is made of small,unbreakable parts called atoms. He born on 460 BC. He died on 370 BC.HIs theory of structure of the atoms *named the smallest piece of matter an atom *atom is indivisible.*atoms are solid but invisible. -
Ernest Rutherford
Discovered the nucleus. Did Rutherford model and Gold foil and gold fold experiment. He made 2 major conclusion for his gold foil experiment : the nucleus is made of mostly (+)charge and mass. the atom contains a positive piece at center. -
Aristotle
Stated that all substance are made of 4 element
1)Fire 3)Water
2)Air 4)Earth
School had a broad of range of subject, but showed emphasis on study of nature.
Born on 384
Died on 322 -
John dalton
Tansformed democritus ideas into a modern atomic model.All substance is made tiny atom particle called element. The atoms of the same element are atomic idential. Atoms of diffrent elements combine in small, whole # ratios to form adnpounds. Best known for his pioneering work in the developement for mordern atomic theory. -
J.J thomson
Discovered the eletron. Conducted the cahode ray experiment. Was an English physicist. Cathode ray tube experiment :
By adding an eletric charge he found that moving piece were (negative) positive. Plum pudding model : Displays electrons embeded in a sphere of positive material. -
Robert Millikan
Determined the amount and charge of eletron. Conducted the oil drop experiment by measuring the effect of an electric field on every small oil droplets. From the velocity of the drop and the charge on the plates, he calculated the mass on an electron. -
Sir James
Confirmed the existense of neutron in the nucleus. The atom is mostly empty space. The atom consists 2 regions. Nucleus in center and contains prootons and neutron. -
Neils bohr
Proposed that an eletron found only in specific circular paths, or orbit around the nucleus. Bohrs model: Reffered to as planetary model because eletrons move around the nucleus like planet around the sun.
