# What is the principal quantum number (n) for the valence electrons in phosphorus?

##### 1 Answer
May 27, 2018

$3$

#### Explanation:

Well, phosphorus has an electron configuration of:

$\left[N e\right] 3 {s}^{2} \setminus 3 {p}^{3}$

The outermost shell is the third shell, so here, $n = 3$.