| A | B |
|---|
| Democritus | first to talk about atoms, a particle too small to divide |
| Isotope | same number of protons and electrons , different number of neutrons |
| John Dalton | father of modern atomic theory |
| J. J. Thomson #1 | discovered electrons |
| Ernest Rutherford #1 | discovered the nucleus |
| Neils Bohr | believed electrons fell into specific orbits |
| Today's atomic theory | say electrons are found in clouds around the nucleus |
| atoms | smallest part of an element |
| J. J. Thomson #2 | cathode ray tube experiment |
| Ernest Rutherford #2 | gold foil experiment |
| electrons | negatively charged particles |
| nucleus | positively charged center of the atom |
| Dalton's Theory | atoms make up everything, form componuds, & atoms of each element are alike |
| mass number | total atomic masses of an atoms protons and neutrons |
| Uranium-235; does the "235" refer to the mass number, the atomic number, or the atomic mass | mass number |
