## Chemistry: Molecular Approach (4th Edition)

(a) $[Ar]3{{d}^{3}}4{{s}^{2}}$ (b) $[Xe]4{{f}^{14}}5{{d}^{5}}6{{s}^{2}}.$ (c) $[Kr]4{{d}^{10}}.$
The transition elements have the unique properties to exhibit variable valencies ranging from $~0\text{ }to\text{ +7}.$ This unique characteristic of transition elements is due to the availability of vacant d orbitals in transition metals. (a) Ground state electron configuration of vanadium is $[Ar]3{{d}^{3}}4{{s}^{2}}.$ Hence, the highest possible oxidation state is obtained by the loss of all s and d electrons. So, maximum oxidation state for $V\text{ }is\text{ }+5$. (b) The ground state electron configuration of rhenium is $[Xe]4{{f}^{14}}5{{d}^{5}}6{{s}^{2}}.$ Hence, the highest possible oxidation state for Re would $be\text{ +7}$, which can be acquired by the loss of five electrons from the 5d orbital and two electrons from the 6s orbital. (c) The ground state electron configuration of palladium is $[Kr]4{{d}^{10}}.$ It can lose a maximum of four electrons to obtain the highest oxidation state of +4.