Unit 2- Chemistry Test
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16 terms
Terms | Definitions |
|---|---|
 atom | smallest particle of matter |
| Democritus | hypothesized that matter could be subdivided again and again until it would reach a particle that could not be divided. atomos- indivisible |
| aristotle | hypothesized that mater was "continuous" in nature. Divided again and again an infinite number of times and you would never reach a particle that cannot be further divided |
| Robert Boyle and Isaac Newton | first men to question the validity of Aristotle's hypothesis |
| John Dalton | developed the atomic theory. conceived the atom that was solid sphere, like a pool ball |
| J.J. Thomson | discovered both electrons and protons by means of his CATHODE RAY EXPERIMENT plum pudding model |
| Cathode ray experiment | electrons and protons, embedded electrodes in the ends of a sealed glass tube and passed an electrical current through it. |
| cathode | negative electrode |
| anode | postive electrode |
| electrode | small pieces of metal through which electrical current is input |
| gold foil experiment | proved that the atom was mostly space and that all positive charge was located in a very small central |
| Neils Bohr | suggested the "planetary model" of the atom in which the electrons orbited the nucleus like the planets and the sun. suggested the location of the electrons in an atom |
| atomic number | number of protons found in the nucleus of an atom |
| mass number | sum of the protons and neutrons in the nucleus of an atom |
| atomic mass | a weighted average of all the masses of all the isotopes of that element by their percentage of abundance |
| chemical configuration | Mass Number Charge symbol atomic number |
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