Confused about Fe's (Iron) total valence electrons

[vuongnaomi1L]

Since Fe is a transition metal and has unfilled d orbitals, it can have up to 12 valence electrons when bonding; for example in the molecule Ba(FeBr4)2. Usually, when it is not bonded, it just has 2 valence electrons.

Can someone confirm or deny whether the statement above is correct?

[Hazelle Gunawan 3G]

I think if you're counting the d subshell, then technically it has 8 valence electrons? I was actually discussing this in a review session earlier, and the people in the chat said that for transition metals you would count the d subshell as part of the valence electrons. But I think Fe usually exists in a 2+/3+ oxidation state. Not sure on this though so I would definitely appreciate any clarifications anyone else has!

[Yu Jin Kwon 3L]

I was also in the review session, and we talked about Chromium ([Ar] 3d^5 4s^1) in particular and how it has 6 valence electrons. First, I also thought you would only count the electrons in the final n level (4, so 1 valence electron), but you apparently count everything outside the bracket (5 electrons (from 3d) + 1 electron (from 4s), so 6 valence electrons). I feel like maybe this only applies to transition metals though because something like Gallium has only 3 valence electrons, but its electron configuration is [Ar] 3d^10 4s^2 4p^1, so for this one we only look at the final n=4 electrons.