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Period: 100 to
atomic model
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400
the alchemists
Aristotle and Plato favored the earth, fire, air and water approach to the nature of matter. Their ideas held sway because of their eminence as philosophers. The atomos idea was buried for approximately 2000 years -
400
plato
come up with the word element -
400
billiard ball
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430
democritus
He asked: Could matter be divided into smaller and smaller pieces forever, or was there a limit to the number of times a piece of matter could be divided? -
Lavoisier
His results showed that the mass gained by the metal in forming the calx was equal to the mass lost by the surrounding air . -
john Dalton
He deduced that all elements are composed of atoms. and did experiments that eventually led to the acceptance of the idea of atoms. -
dmitri mendeleev
he had the creation of the periodic table -
the curies
pierre and marie conducted pioneering research on radioactivity. -
Plum Pudding Model
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albert einstein
In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers. -
Ernest Rutherford
The nucleus is tiny compared to the atom as a whole. -
Neils bohr
In 1913, the Danish scientist Niels Bohr proposed an improvement. In his model, he placed each electron in a specific energy level. -
Bohr model
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solar system atomic model
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hernry G. J. Mosely
he used self-built equipment to prove that every element’s identity is uniquely determined by the number of protons it has. His discovery enabled him to predict confidently the existence of four new chemical elements, all of which were found. -
electron cloud model
