AS: Chem Hund's Rule

In As chemisrty when using hund's rule to find out the electronic configuration of subshells how would I find out the configuration for an ion. For example: Ca^2+ or S^2-

Reply 1

solider88

ok i get it. If it is a + ion then add the +1e to the configuration. If its - ion then -1e from the configuration.

example:
CL + e ======> Cl ^ -
1s^2 2s^2 2p^6 3s^2 3p^5 + e = 1s2 2s2 2p6 3s2 3p6

Reply 2

ad absurdum

You have the correct answer for the chlorine ion.

You just need to remember the basics of how the shells are filled. If you have a chlorine arrangement and you added another electron, where would it go? Keep in mind the aufbau principle (electrons fill lowest energy orbitals first) and Hund's Rule (electrons fill orbitals singly with parallel spins before pairing up) and you won't go far wrong.

If you were doing a positive ion (I'm only talking about the first three periods here) think about the order that you added the electrons in, they are removed the same way. Things get a little more complicated once you get onto d-block and f-block elements but I'm not sure if this is part of your course in England.

It might help to think about what element the ion has the same arrangement as, but as I said things get a little more complicated once we start thinking about d and f subshells so only use this for the first 20 or so elements.

Reply 3

vinny221

Boss

ok i get it. If it is a + ion then add the +1e to the configuration. If its - ion then -1e from the configuration.

example:
Cl + e ======> Cl ^ -
1s^2 2s^2 2p^6 3s^2 3p^5 + e = 1s2 2s2 2p6 3s2 3p6