Silver is considered a transition element because it has partially filled d orbitals in its electron configuration. Transition elements are characterized by the filling of inner d orbitals as electrons are added. The d orbitals are part of the second and third energy levels (shells) of an atom.
The electron configuration of silver (Ag) is [Kr] 4d^10 5s^1. In this configuration:
The fact that silver has electrons in the 4d orbitals places it in the transition metals section of the periodic table. Transition elements generally have incomplete d orbitals, and as electrons are added, they fill these orbitals in a way that results in varying oxidation states.
In the case of silver, it exhibits a +1 oxidation state more frequently, but it can also display a +2 oxidation state. The variability in oxidation states and the presence of partially filled d orbitals are key characteristics that classify silver as a transition element.
