Question #67208

1 Answer
Stefan V.
Feb 7, 2015

Phosphorus is located in group 15 of the periodic table and has an atomic number equal to 15. This means that a neutral phosphorus atom has a total of 15 electrons.

The ground state electron configuration for phosphorus is

![http://www.creative-chemistry.org.uk/alevel/module1/trends6.htm](useruploads.socratic.org)

"P": 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(3)

I'll use the noble gas shorthand notation from this point on.

"P": ["Ne"] 3s^(2) 3p^(3)

Now, an excited state configuration has one electron promoted from a lower to a higher energy level. Looking at the ground state configuration, you could have one electron from the "3s" sub-level promoted to the "3p" sublevel. The electron configuration will be

"P": ["Ne"] 3s^(1) 3p^(4)

Another possibility is to have one electron from the "3p" sub-level promoted to the "4s" sub-level

"P": ["Ne"] 3s^(2) 3p^(2) 4s^(1)

Yet another possibility is to have one electron from the "3p" sub-level promoted to the "3d" sub-level, skipping the "4s" sub-level altogether

"P": ["Ne"] 3s^(2) 3p^(2) 3d^(1)

Read more on how to determine excited state configurations here:

http://socratic.org/questions/how-do-you-determine-excited-state-electron-configuration

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