| A | B |
|---|
| neutral atom | protons = electrons |
| Dalton's atomic theory | Chemical reactions are combination, separation & rearrangment of atoms. |
| Law of Conservation of Mass | mass of products = mass of reactants |
| light emitted | electrons return to ground state |
| calcium-20 | 1s2 2s2 2p6 3s2 3p6 4s2 |
| isotopes | atoms of elements with different neutrons numbers |
| Law of Multiple Proportions | Elements combine in mass ratios that are expressed in small whole number ratios |
| Law of Definite Composition | All samples of a compound have the same ratio of elements |
| nucleus | contains nearly all of atom's mass |
| electron cloud | contains nearly all of atom's volume |
| atomic number | number of protons |
| mass number | number of protons + number of neutrons |
| Pauli's Exclusion Principle | An orbital can hold no more than 2 electrons |
| Hund's Rule | Electrons fill all sublevels before pairing |
