Unpaired electrons/transition metal ions

[Sir Anonymous]

Hi,

My question concerns this homework problem I have:

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"How many unpaired electrons are there in the following transition metal ions. Write your answer as a sequence of numbers, for example, 23542141.

A) Mn5+ B) Fe3+ C) V5+ D) Fe4+ E) Mn4+ F) Ni4+ G) Cu4+ H) Sc2+ "

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My text wasn't really helpful. So, wouldn't these be the answers for e/one? 25043651

For example, for Mn5+ I picked 2 (2 unpaired e-'s) b/c the config. is 4s2 3d5. so that is 5 + 2 = 7 unpaired electrons, minus 5 (Mn5+) = 2. Is this the right way to think about it?

And for instance, for V5+ I said..... since it's s2 d3, that = 5 unpaired electrons, and so 5-5 = 0. So am thinking it through the right away? And what about Cu4+, since it is one of the exceptions having a config of s1 d10?


Thanks in advance for any help

[Sir Anonymous]

just wondering, is this kind of problem beyond the ken of the chemistry experts on this board?

[charco]

you must remember that transitions metals lose the 4s electrons FIRST before losing the 3d electrons.

eg Mn2+ is [Ar]4sº 3d5 - therefore 5 unpaired electrons