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Period: 500 to 505
Democritus
The greek philosopher, Democritus, lived from 460-370 BC. He was the first to suggest that matter could not be infintely divided. He stated that atoms could not be created, destroyed or divided any further. However, he could not figure out how they were bonded. -
505
Democritus
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Period: 510 to 520
Aristotle
Aristotle was another Greek philosopher who lived from 384-322 BC. He disagreed with Democritus due to his personal views on nature. He believed that atoms never existed snd could not move through empty space. -
520
Aristotle
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Period: to
Dalton
Dalton was an English school teacher who marked the beginning of the development of the modern Atomic Theory. He took Democritus' ideas about matter and changed them based on his personal research. He revived the word atom. He later stated that atoms were the smallest particles of matter and are indivisible and indestructable. -
Dalton
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Period: to
JJ Thompson
Thompson designed a series of CRT experiments to determine the ratio of the particles charged to its mass. He concluded that the mass of the particle was much less than that of the hydrogen atom, which disproved Dalton's theory that atoms were indivisible. He recieved a Nobel Prize in 1906 for his research. -
Period: to
Robert Millikan
Millikan designed an oil drop apparatus to determine charges of electrons. He determined that the magnitude of the charge of electrons was 1.602x10- coulombs. The charge that he ended up with was equal to a single unit of negative charge. This means the electron carried a charge of -1. He also discovered the mass of electrons using the ratio: 9.1x10- -
Period: to
Rutherford
Rutherford studied how positively charged a-particles interacted with solid matter. He designed an experiment to see if the particles would be deflected as they passed through a thin sheet of gold foil. Based on his results, he stated that Thompson's experiment was incorrect. He calculated that an atom was basically just empty space for electrons to move around in. There had to be a place for a positive charge and a majority of the mass of an atom to reside. -
Rutherford cont.
He also claimed that it was contained in a tiny space in the center of the atom and called the spot nucleus. -
Thomson
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Millikan
