The elements which have partially filled d or f subshells in any common oxidation state are called as the transition elements. Silver (the Atomic number is 47 and electronic configuration is [Kr] 4d¹⁰5s¹) has a completely filled 4d orbital in its ground state but has two oxidation states (+1, +2).

In the +1 oxidation state, an electron is removed from the s-orbital and in +2 oxidation state, one electron from d-orbital is also removed. Thus, the d-orbital now becomes partially filed (4d⁹). Hence, it is a transition element.