2s2
Third energy level
8
Valence.
Helium
7 electrons
2s
The 3rd energy level is the highest occupied energy level for chlorine with seven electrons.
Sr has two electrons in the highest occupied energy level
1s
2
The highest occupies energy level in aluminum is the 3rd energy level. Its electron configuration is 1s22s22p63s23p1.
Third energy level
the period number tells which is the highest energy level occupied by the electrons
4
8
Eight.
Valence.