4
2s
7
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
5 valence electrons.
The number of electrons it has in the highest occupied energy level.
A filled highest occupied principal energy level
2
2s2
The highest occupies energy level in aluminum is the 3rd energy level. Its electron configuration is 1s22s22p63s23p1.
Third energy level