| # | Symbol | Name | Atomic Mass | Category |
|---|---|---|---|---|
| 11 | Na | Sodium | 22.99 | Alkali Metals |
| 12 | Mg | Magnesium | 24.305 | Alkaline Earth Metals |
| 13 | Al | Aluminium | 26.982 | Post-Transition Metals |
| 14 | Si | Silicon | 28.085 | Metalloids |
| 15 | P | Phosphorus | 30.974 | Other Non-Metals |
| 16 | S | Sulfur | 32.06 | Other Non-Metals |
| 17 | Cl | Chlorine | 35.45 | Halogens |
| 18 | Ar | Argon | 39.95 | Noble Gases |
8 elements