# What is the second quantum number of a #1s^2# electron in phosphorus #1s^2 2s^2 2p^6 3s^2 3p^3#?

##### 1 Answer

Mar 17, 2016

#### Explanation:

As you know, **four quantum numbers** are used to describe the position and spin of an electron in an atom.

In your case, you want to know the value of the *angular momentum quantum number*, **1s-orbital**.

As you can see, the angular momentum quantum number depends on the value of the *principal quantum number*, **energy level** on which the electron is found.

The **1s-orbital** is located on the *first energy level*, hence the number

Since

#l = 0, 1, 2, ..., (n-1)" "# and#" "n = 1#

you will have only **one possible value** for

An **s-orbital** will **always** have