Question

fill in the blank question
the energy levels contained within a principal energy level are called

Explanation:

In atomic structure, within a principal energy level (denoted by \(n = 1,2,3,\cdots\)), there are sub - levels (denoted by \(s,p,d,f\) etc.). For example, when \(n = 2\), there are \(2s\) and \(2p\) sub - levels. The principal energy level gives the general energy of the electrons in that level, and the sub - levels further divide the energy distribution within that principal level.

Answer:

sub - levels