| Period | Group | |
|---|---|---|
| ◀ 2 ▶ ▶▶ | ||
| 1 |
2
He
Helium
1s2
|
|
| 2 |
4
Be
Beryllium
[He] 2s2
|
|
| 3 |
12
Mg
Magnesium
[Ne] 3s2
|
|
| 4 |
20
Ca
Calcium
[Ar] 4s2
|
|
| 5 |
38
Sr
Strontium
[Kr] 5s2
|
|
| 6 |
56
Ba
Barium
[Xe] 6s2
|
|
| 7 |
88
Ra
Radium
[Rn] 7s2
|
Tip: Hover over an element to compare its electron configuration to that of the element below it.