**The quantum numbers**

#n = 3# is the **principal quantum number**.

The "3" tells you that the electron is in the third energy level.

#l = 1# is the **secondary quantum number**.

#l# can have any integer value from #0# to #n"-1"#. Since #n=3#, the allowed values of #l# are #0, 1, 2#.

The value of #l# tells you the shape of the orbital.

- #l=0# corresponds to an #"s"# orbital.
- #l=1# corresponds to a #"p"# orbital.
- #l=2# corresponds to a #"d"# orbital.

The value #n = 3, l = 1# tells us that this is a #"3p# electron.

#m_l# is the **magnetic quantum number**.

#m_l# tells us the orientation of the orbital in a magnetic field.

#m_l# can tale any integer value from #+l# to #"-"l"#. The three allowed values of #-1, 0, "and" +1# correspond to the three #"3p"# orbitals.

#"s"# is the **spin quantum number**. It tells us the relative direction of the spin of the electron on its axis.

#"s"# can have only the values #"+½"# or #"-½"#.

**Name the element**

We are looking for an element that has a #"3s"# electron in its configuration.

From the Periodic Table. that could be any element with an atomic number greater than 12.

Two of the elements in your list have a #"3p"# electron:

#"S"# has the electron configuration #"1s"^2 "2s"^2 "2p"^6 "3s"^2 "3p" ^4#.

#"K"# has the electron configuration #"1s"^2 "2s"^2 "2p"^6 "3s"^2 "3p" ^6 "4s"#.

Both sulfur and potassium contain a "#3p"# electron in the ground state.