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26 Cards in this Set
- Front
- Back
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Democritus |
thought that eventually you would end up with a particle that could not be cut |
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Aristotle |
Didn't believe that a particle could make up all substances found in nature |
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atom |
smallest particle into which an element can be divided and still be the same element |
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electrons |
negatively charged partices |
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nucleus |
small dense center that has a positive charge and is surrounded by moving elecrons |
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protons |
positively charged particles in the nucleus |
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neutrons |
uncharged particles |
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electron cloud |
area around the nucleus |
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Dalton's theory |
matter is made up of atoms atoms cannot be created, divided, or destroyed all atoms of a certain substance are identical every substances is made up of atoms combined in certain ways |
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J.J. Thompson |
Chocolate chip cookie model Thought that atom was a positive sphere with electrons mixed through it |
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Ernest Rutherford |
Found out that the nucleus is made up of smaller particles |
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Niels Bohr |
atom has a positive nucleus surrounded by electrons |
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atomic number |
number of protons in the nucleus of an atom |
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mass number |
total number of protons and neutrons in an atoms nucleus |
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isotopes |
atoms of the same element that have different number of neutrons |
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periodic table |
Mendeleev's arrangement of the elements |
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chemical symbol |
abbreviation for the elements name |
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average atomic mass |
weighted average of the masses of all the naturally occurring isotopes of that element |
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metals |
elements that are shiny and conduct electricity well |
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nonmetals |
poor conductors of heat and electricity |
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metalloids |
elements that have some properties of nonmetals |
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malleable |
able to be formed into different shapes |
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ductile |
they can be made into wires |
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group |
vertical column of the periodic table |
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family |
elements in the same group have the same properties |
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period |
each horizontal row of elements on the periodic table |
