posted by Shadow .
Is this always true, sometime true, or never true?
The orbitals of a principal energy level are lower in energy than the orbitals in the next higher principal energy level.
-I'm thinking sometime true but I can't figure out how to explain why it sometime true. Thanks
I think you're right. It is true sometimes but not all the time.
The best way I think is to show examples.
12Mg = 1s2 2s2 2p6 3s2
Here the 1s orbital is lower than the 2s and they are lower than the 3s etc.
19K = 1s2 2s2 2p6 3s2 3p6 3d0 4s2
Here the 1s is lower than the 2s and those are lower than the 3s and the 4s BUT the 4s level is lower than the 3d.