| A | B |
|---|
| Mendeleev | Periodic table arranged by mass and similar properties. |
| period | Row on periodic table. |
| group | Column on periodic table. |
| periodic law | Pattern of repeating properties in a periodic table. |
| amu | atomic mass unit - units used for mass of the atom. |
| metals | Left of the stair-steps. Able to conduct heat and electricity. Form cations. |
| transition metals | Largest section of metallic elements on the periodic table. |
| non-metals | Right of the stair-steps. Unable to conduct heat and electricity. Form anions. |
| metalloids | The stair-steps. Share properties of both the metals and non-metals. |
| valence electrons | Electrons found in the outermost orbital. |
| alkali metals | Most reactive metals. Valence of 1. |
| alkaline earth metals | Valence of 2. Metals most commonly found in the human body. |
| halogens | Most reactive non-metals. |
| noble gases | Non-reactive, or inert gases. |
| electron configuration | The number of electrons in each orbital (energy level). |
