Question

What electron configuration repreents the first excited state of phosphorus?

Answer 1

Answer:

Option C:

1s2 2s2 2p6 3s1 3p4

Explanation:

At a ground level, Phosphorous has an electronic configuration of 1s2 2s2 2p6 3s2 3p3 (using the spdf notation).

Once the atom becomes excited, an electron from the 3s sub-level will gain energy and jump over to the 3p sub-level, making the configuration 1s2 2s2 2p6 3s1 3p4.

The number of electrons at the 3p sub-level will now become 4 because of the addition of the new electron while the number of atoms at the 3S sub-level will reduce to 1 because an electron left this sub-level.