nickel
scandium
Scandium is a transition metal with atomic number 21. Its electronic configuration is [Ar] 3d1 4s2.
In its compounds, scandium typically exhibits only the +3 oxidation state, as the loss of all three valence electrons (one from the 3d orbital and two from the 4s orbital) results in the Sc3+ ion.
Other transition metals like zinc, nickel, titanium, and iron can exhibit multiple oxidation states, including +2, +4, etc., but scandium is the only one that predominantly exhibits the +3 oxidation state.