Term
| What did Democritus do as a scientist and when? |
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Definition
| 400 BC- He was the first one to suggest existence of atoms. |
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Term
| Who was John Dalton, and name one of his correct theories? |
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Definition
He was an English teacher who studies ratios in which elements combined in chemical reactions. Correct theories:
-Atoms of the same element are identical
- All elements have indivisible, tiny particles called atoms. |
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Term
| What is the relative size of atoms? |
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Definition
| 100,000,000 Cu atoms placed side by side are no longer than 1 cm!! |
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Term
| What is the charge of any atom and why? |
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Definition
| Neutral, because if it wasn't, objects would shock us everytime we touch them! |
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Term
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Definition
| He discovered the existence of the electron. |
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Term
| What did Robert Millikan do? |
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Definition
| He calculated the mass of electrons. |
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Term
| What did E. Goldstein discover and how? |
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Definition
| He found protons by studying cathode ray tubes. |
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Term
| What did James Chadwick do? |
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Definition
| He confirmed the existence of the neutron. |
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Term
| *What did Ernest Rutherford do? |
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Definition
| He tested the theory of atomic structure, but using a gold foil experiment. He concluded that most of an atom is empty, with a dense, positive nucleus. |
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Term
| What is the atomic number of an element? |
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Definition
| The number of protons in the atom. |
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Term
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Definition
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Term
| What is the mass number of an element? |
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Definition
| The number of protons + the number of neutrons. |
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Term
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Definition
| Atoms that have the same number of protons but a different number number of neutrons. |
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Term
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Definition
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Term
| **Who was Mendeleev and who was Mosely? Which way is the periodic table set up today? |
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Definition
Mendeleev- 1st arranged elements in a table (BY ATOMIC MASS). Predicted properties of elements not yet discovered.
*Moseley- (ARRANGED BY ATOMIC NUMBER) We use MOSELEYS TABLE (THE PERIODIC TABLE TODAY) |
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Term
| How did the periodic table get its name? |
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Definition
| Because of elements arranged periodically by properties. |
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