Electron configurations of ions

Rebecca Epner 4A
Posts: 53
Joined: Sat Aug 17, 2019 12:18 am

Electron configurations of ions

Why is it important to first write the ground state electron configuration of an element before determining the electron configuration of an anion or cation?

Jorja De Jesus 2C
Posts: 121
Joined: Sat Jul 20, 2019 12:15 am

Re: Electron configurations of ions

I don't think you have to write them in a certain order; it just depends on what is being asked for. If you are asked for the ground state electron configuration, you just write that out. If it asks for the electron configuration for a cation or anion, you will probably have to write the ground state version out anyway because all you would have to do after is remove electrons from the outer orbital if it is a cation and add electrons to the outer orbital if it is a anion.

Christine Honda 2I
Posts: 116
Joined: Sat Sep 14, 2019 12:17 am

Re: Electron configurations of ions

I think it is important to write the ground state first so that we can see which orbital has the highest energy so we can easily see where to remove or add electrons. It may not be totally necessary though, more just useful.

SarahCoufal_1k
Posts: 102
Joined: Thu Jul 25, 2019 12:17 am

Re: Electron configurations of ions

It's mainly so you won't mess up and remove it from the wrong shell. This is especially important when you get to the fourth row and start using the D block.

Because you would fill up an electron from low to high energy, 4S starts out lower energy than 3d, but once 3d has an electron now it's a lower energy. So it would go first in the configuration. When forming a cation and you remove an electron, you want to remove the highest energy first which is 4s, not 3d.

Ex) Fe to Fe+
Fe: [Ar]4s2 3d6 --- then rearrange it low to high energy level -----> [Ar]3d6 4s2
Now when forming the cation remove from the electron from the highest energy level first which would be 4s2
so Fe+=[Ar]3d6 4s1

Areena H 2K
Posts: 81
Joined: Wed Dec 05, 2018 12:18 am

Re: Electron configurations of ions

I think it just helps you find which shells you are removing the electrons from. You don't have to write out the ground state configuration if a question doesn't ask but it just helps you make less mistakes especially when we get into the 4th row and remember that we remove electrons from the 4s energy subshell before the 3d subshell