# How many electrons are present in a 4p orbital?

Jul 3, 2016

Two electrons.

#### Explanation:

A $4 p$ orbital, which is part of the $p$ subshell located on the fourth energy level, can hold a maximum of two electrons.

In fact, any orbital, regardless of its energy level, subshell, and orientation, can hold a maximum of two electrons, one having spin-up and one having spin-down.

This is the case because according to the Pauli Exclusion Principle, two electrons located in an atom cannot share a complete set of four quantum numbers.

To the level of an orbital, this comes down to one of the two electrons that share an orbital having spin-up, which is given by the spin quantum number ${m}_{s} = + \frac{1}{2}$, and the other having spin-down, which is given by ${m}_{s} = - \frac{1}{2}$.

Now, the $4 p$ subshell contains a total of three $4 p$ orbitals, $4 {p}_{x}$, $4 {p}_{y}$, and $4 {p}_{z}$.

Since each of those $p$ orbitals can hold a maximum of two electrons, the $p$ subshell can hold a maximum of

3 color(red)(cancel(color(black)("p orbitals"))) * "2 e"^(-)/(1color(red)(cancel(color(black)("p orbital")))) = "6 e"^(-)

Therefore, you can say that a $4 p$ orbital can hold a maximum of two electrons and the $4 p$ subshell can hold a maximum of six electrons.