Atoms Chapter Test Prep
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27 terms
Terms | Definitions |
|---|---|
 Atom | the smallest unit of matter, builds pretty much everything |
| atomos | Democritus coined this Greek term meaning 'indivisible' |
| atomic theory | John Dalton came up with the first one of these, it had five postulates |
| negative corpuscles | what Thomson called electrons |
| electrons | negative particles in atoms, very little mass and inertia |
| plum pudding model | what Thomson's model was often called |
| cathode ray tube | used in Thomson's experiment that discovered electrons |
| gold foil | used in Rutherford's experiment and was shot at by particles |
| nucleus | the center of an atom with protons and neutrons |
| electron energy levels | specific places where electrons were found in the Bohr model, also called the planetary model |
| protons | positive particles in atoms, have a mass of 1 AMU |
| neutrons | neutral particles in atoms, have a mass of 1.0000001 AMU |
| atomic mass unit | a metric unit that measures mass, one is equal to the mass of 1 proton |
| ion | atom with a different number of electrons than protons |
| cation | positively charged ion |
| anion | negatively charged ion |
| isotope | comparison of atoms that are the same element but have different mass numbers |
| atomic number | equivalent to the number of protons in an atom or the number of the atom on the periodic table |
| radioactive | way of describing an atom with an unstable nucleus |
| mass number | the mass of a single atom of an element |
| electromagnetic force | electrons repel each other, protons repel each other, protons and electrons attract (elements with more protons are more unstable) |
| gravitational force | weakest force, strong over distances, "eternal force", affects everything because everything has mass |
| strong force | the strongest force, comes from the center of a star, nuclear bomb, supernova, holds protons together. Without this force we wouldn't exist because there would only be Hydrogen. |
| weak force | the second weakest force, involved in radioactive decay, causes neutrons to turn into protons and electrons, turns elements into other elements |
| isotope notation | way of writing an atom so that you can see what element it is and also the mass number and charge so that atoms can be compared |
| electron cloud | fuzzy region of an atom surrounding the nucleus where electrons can be |
| Heisenberg Uncertainty Principle | states that you never be sure of the location or direction of electrons |
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