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Ch. 11- science HH
Ch. 11 study guide for test
| Question | Answer |
|---|---|
| What is an atom | Smallest particle into which an element can be divided and still keep it properties. |
| Democritus | 440 B.C.E., Greek philosopher,thought that you couldn't cut a matter forever. |
| John Dalton | 1803,based ideas on experiments.stated: all substances are made of atoms, all atoms of one atom are exactly alike, and atoms can join other atoms to make new substances. Atoms can't be created,destroyed, or divided. |
| J.J Thomson | 1897, british scientist discovered negatively charged particles that are known as electrons. Cathode-ray experiment. (plum pudding) |
| Ernest Rutherford | 1911, the center of an atom is a tiny, positively charged part called a nucleus. (gold foil experiment) |
| Neil's Bohr | 1913, Danish scientist discovered that electrons move around in energy levels, paths. |
| Erwin shrödinger and Werner Heisenberg | Austrian and German scientists, discovered that electrons are found in regions inside the atom called electron clouds. ( modern theory) |
| Atoms | .00000003 cm big. Made up of protons, neutrons, and electrons. |
| Protons,neutrons,electrons | Protons-positively charged particles in the nucleus Neutrons- nonelectrical charged particles Electrons-negatively charged particles in atoms. |
| Isotopes | Atoms that have the same number of protons but have a different number of neutrons. Unstable atom, radioactive isotope.idetify isotopes by mass number. |
Created by:
helen_ih
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