Chemistry - Oxidation numbers (states) of transition metals
Oxidation numbers (states) of transition metals
The main group (non-transition) metals generally strive for noble gas
electron arrangements in their compounds and so usually have single
oxidation states numbers,
e.g. Ca 1s2s2p3s3p4s becomes Ca 1s2s2p3s3pwith the oxidation number +2
In the first row transition metals, the 3d and 4s subshells have very
similar energy and electrons in both subshells may be lost to form ions.
Ions with +2 and +3 charges are common throughout the first transition
Higher oxidation states such as +4, +5, +6 and +7 do not actually occur in
monatomic ions, but tend to occur in oxides and oxide ions. For example, in
chromate CrO4 and dichromate Cr2O7, the oxidation state of chromium is +6.
These 'molecule ions' involve sharing electrons with oxygen atoms.
Manganese - 1s2s2p3s3p4s3d or 1s2s2p3s3p3d4s - exhibits the highest
oxidation state of the transition metals, +7 in the permanganate ion, MnO4.
All members of the first transition series except Sc and Zn exhibit
multiple oxidation states. The wide range of oxidation states can be
attributed to the partially-filled d-subshell and the similarity in energy
of the 4s and 3d subshells.
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