| A | B |
|---|
| Pauli Exclusion Principle | a maximum of two electrons can occupy each orbital, and these electrons must have different spin quantum numbers |
| Hund's Rule | the most stable arrangement of electrons is that with the maximum number of unpaired electrons, all with the same spin quantum number |
| Aufbau Principle | electrons in an atom will occupy the lowest energy orbitals available |
| periodic law | the physical and chemical properties of elements are periodic functions of their atomic numbers |
| metals | any element that is a good conductor of electricity |
| non metals | bad conductors of electricity |
| semiconductors | intermediate electrical conductivity |
| alkali metals | highly reactive, react rapidly with water to form ydrogen and alkaline solutions and that burn in air |
| alkaline earth metals | reactive |
| halogens | nonmetallic, combines with many metals to form salts |
| noble gases | low reactivity |
| periodic trend | physical or chemical properties that are similar in a trend |
