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

#l=0#

Explanation:

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

![figures.boundless.com](useruploads.socratic.org)

In your case, you want to know the value of the angular momentum quantum number, #l#, for an electron located in the 1s-orbital.

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

The 1s-orbital is located on the first energy level, hence the number #1# used in its name.

Since

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

you will have only one possible value for #l#, and that is #l=0#.

An s-orbital will always have #l=0#, regardless of energy level.

![chemwiki.ucdavis.edu)