Hi guys! This has been bothering me for the entire quarter so naturally I'm inquiring about it at the very last minute. Have the electron configurations on the tests and in the textbook been in the wrong order?
When I learned in high school and for every resource I've used online, the order goes diagonally through the orbitals. Ex:
1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d10 etc...
This would produce the orbital order: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 etc.. But the way we've been practicing has been 1s2 2s2 2p6 3s2 3p6 3d10 4s2 etc.
An example of this from the textbook problems would be 2A.19 part a, where the textbook answer says that the ground state electron configuration for Sb3+ should be [Kr]4d10 5s2, but the way I have it is flipped, [Kr}5s2 4d10, because the 5s2 orbital is lower in energy than the 4d10 orbital. I attached a diagram that helps explain what I'm talking about.
Which way is correct? Thanks in advance :')
Order for Electron Configurations
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Re: Order for Electron Configurations
Its a little misleading because of the numbers going out of order but 4d10 will come first because 4d is a lower energy than 5s. So the correct order would be [Kr]4d105s2. I believe there are certain exceptions where the 5s can be written before but I do not think we need to know those. I would just try to remember that 4d has lower energy hence itll come before 5s.
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Re: Order for Electron Configurations
One way I think about why we write it the way we have been doing in class with 3d written before 4s is because the objective is to write the orbitals in order of increasing energy, so as move from left to right, the energy of each orbital is increasing. Therefore, even though we technically fill 4s before 3d, we write it to the right of 3d because it's orbital has higher energy. Hope this helps!
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