# Question #f8cff

Apr 14, 2016

The $4 s$ subshell has a lower energy level compared to the $3 d$ because it is closer to the nucleus.

#### Explanation:

The $4 s$ subshell is overlapped by the $3 d$ subshell so it is closer to the nucleus.

Imagine the nucleus as your body. The $4 s$ subshell would be your t-shirt, and the 3d subshell would be your shirt. The
3d is further away from your body so it has a higher energy level.

THE key point is:

The further away a subshell is, the more energy the electrons need to have in order to stay within it's region.