The alkaline earth metals are a series of elements that make up Group 2 of the periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). The alkaline earth metals are a prime example of group trends in properties in the periodic table, with a trend of similar for behavior going down the group. Here is the number of Electrons per shell:
| Z | Element | No. of electrons/shell |
|---|---|---|
| 4 | Beryllium | 2, 2 |
| 12 | Magnesium | 2, 8, 2 |
| 20 | Calcium | 2, 8, 8, 2 |
| 38 | Strontium | 2, 8, 18, 8, 2 |
| 56 | Barium | 2, 8, 18, 18, 8, 2 |
| 88 | Radium | 2, 8, 18, 32, 18, 8, 2 |
Alkaline earth metals will react readily with halogens.