Transition elements, such as chromium, are likely to have what type of oxidation number?

Dec 30, 2017

All of the above! Often, $+ 2$, $+ 3$, or $+ 4$, but anything from $- 4$ to $+ 9$ is possible.

Your guess is as good as mine. Here are all the possible oxidation states of every non-$f$-block transition metal. Bolded states are common to that metal.

It seems like the most common oxidation states are:

• $+ 2$ for most of the 1st row transition metals.
• $+ 3$ and $+ 4$ for most of the 2nd row transition metals.
• $+ 4$ for most of the 3rd row transition metals.

That should make sense, because the orbital energies get closer together as we approach higher values of $n$, kind of like in hydrogen atom:

(Although, this convergence is not as patterned in multi-electron atoms, since the angular momentum now present creates non-spherical shapes that complicate the orbital interactions and alter their energies further.)

Still, in general, we can say that for each successive row of transition metals, more orbitals join the valence space, i.e. more electrons take on the role of valence electrons, giving access to higher oxidation states.