Questions on the two exceptions, Chromium and Copper. [ENDORSED]

[Flamingos 3L]

So in the course reader, the jump from Vanadium to Chromium is 3d^3 to 3d^5. Does this mean that three elections were added in this one transition in atomic numbers? (since Chromium is 3d^5 and 4s1)

Also, after Chromium, where is the atom placed? continuing the 3d shell, on the 4s shell, or is it just not placed at all?

Similar questions for Copper.

[Eunnie_Lee_3H]

If you look closely, when it jumps from 3d³ (V) to 3d⁵ (Cr), the 4s² changes to 4s¹. So it seems that as you go from Vanadium to Chromium, one of the electrons from 4s moves to 3d (since 3d⁵ and 3d¹⁰ subshells have lower energy) and another electron is added, turning it from 3d³4s² to 3d⁵4s¹. So no, there weren't an addition 2 more electrons added, it's just that one of them was moved from the 4s shell to the 3d shell. And after Chromium, you just fill up 4s¹ to 4s² for Manganese, then continue adding electrons in 3d until you reach Copper where the same thing happens where an electron from 4s "transfers" to 3d, making it 3d¹⁰4s¹.

[904779609]

Are Copper and Chromium the only exceptions following this rule in the d-block? If not, how do you know whether they are an exception?

[Chem_Mod]

Are Copper and Chromium the only exceptions following this rule in the d-block? If not, how do you know whether they are an exception?

Of the elements you need to know for 14A (only up to first row of transition metals), yes these are the only exceptions.
There are other exceptions: the elements directly below Copper and Chromium on the periodic table follow this same trend, and this also occurs in some of the Lanthanide and Actinide series. The reason why these happen is because the stability of the half filled d orbital/f orbital is greatly favored.