Determining valence electrons for d-block elements [ENDORSED]

[Michelle Pham_3H]

We've started drawing Lewis structures based on our knowledge of electron configurations, and while I'm clear on how many valence electrons s- and p- block elements normally have, is it the same for d-block elements or is that given? Any examples would help too. Thanks in advance!

[snehabhargava]

We are only considered with the valence shell electrons so that is the s and p orbitals and we will only be working with those.

[Vincent Grospe 3C]

The valence electrons (outermost) for d-block elements (transition metals) are based on the number of electrons in the orbital with the highest principal quantum number, which is usually the ns-orbital [not the (n-1)d-orbital].

This goes back to Dr. Lavelle’s lectures on writing ground-state configurations for transition metals, which he explained why (for example) the 4s-orbital would be put after the 3d-orbital despite the building-up principle.

So generally, the transition metals’ valence electrons are usually 2, because the ns-orbital is already filled. But, there are transition metals with half-filled/fully-filled configuration exceptions like copper ([Ar]3d^10 4s^1), which only have 1 valence electron (because the complete filling of the 3d-orbital would give greater stability).

However, transition metals have multiple oxidative states (charges), which changes the number of electrons as well as the number of valence electrons. So overall, it can vary.

[Stephanie tran 1J]

the number of valence electrons in d-block elements is most often equal to their group number which is equal to the number of electrons in the "valence shell." for example, scandium metal's electrons per shell are 2,8,9,2 and its outer shell has only 2 electrons, so the valence electron count of scandium is 2.