# How many valence electrons does phosphorus have?

Nov 3, 2015

5

#### Explanation:

There are two ways to find out. Either you take a look at your periodic table and look at which group number $P$ belongs (this can be seen on upper portion) or you can draw the electron configuration of $P$ atom based on its atomic number (which is 15).

According to the periodic table above, phosphorus belongs to Group 5A. Therefore, Its valence electrons should be 5.

Let's check using the electron configuration:

$1 {s}^{2}$ $2 {s}^{2}$ $2 {p}^{6}$ $3 {s}^{2}$ $3 {p}^{3}$ = 15 electrons = atomic number of $P$

The outermost orbitals, $3 {s}^{2}$ $3 {p}^{3}$, contains 5 electrons.

Thus, valence electrons for $P$ is 5.