According to the Crystal Field Theory, the +3 oxidation state of Chromium is stable can be explained. However, I still am wondering why the same phenomenon does not apply to Molypden and Wolfram (they do not possess the stable +3 oxidation state)?
Moreover, why does Wolfram have the electron configuration of [Ar]5d4 6s2 rather than [Ar]5d5 6s1 like the other two.
In chromium and molybdenum, the sum of the energy required to force two electrons together in the s-orbital (the "correlation energy") and that gained by getting a half-full subshell is less than the energy required to promote an electron from 4s to 3d or from 5s to 4d.
As you go down the periodic table, the s-orbitals get lower in energy relative to other atomic orbitals of the same main shell. This is called a "relativistic contraction".
Because of this effect, the 6s orbital is lower in energy relative to the 5d orbital than the 5s is relative to 4d or the 4s to 3d. Thus, the energy gained by not shoving two electrons into the 6s orbital, plus that from a half-filled 5d subshell, is not enough to compensate for promoting an electron from 6s to 5d.
- Badges
- Science topic
- Similar topics
- Instrumentation Engineering
- Instruments