Scandium is considered to be a transition element though it does not form any coloured ion. Explain.

Explanation

Scandium has one d-electron in its ground state electronic configuration for which it shown + 3 stable oxidation state. In + 3 oxidation state, since there is no d- electrons, d-d transition is not possible for which it does not form coloured ions. Due to the presence of one d-electron in ground state, it is considered as transition element.