Question

On what basis can we say that Cu is a transition element but Zn is not? (Atomic number: Cu = 29, Zn = 30)

Answer 1

Copper (Cu) is classified as a transition element due to its incomplete d-orbital in the +2 oxidation state. In contrast, zinc (Zn) possesses a completely filled d-orbital in its ground state and also in the +2 oxidation state, thus classifying it as a non-transition element. A key characteristic of transition elements is the presence of at least one oxidation state with an incomplete d-orbital.

Answer 2

The participation of electrons from both the (n-1)d and ns subshells in bond formation, owing to their similar energy levels, results in transition elements exhibiting diverse oxidation states. This characteristic enables the formation of multiple oxidation states. Furthermore, the presence of unpaired electrons within the d-orbitals contributes to this range of variability.

Answer 3

Irregular trends in $\text{E\(^0\)}_{M^{2+}/M }$ values from Vanadium to Zinc arise from fluctuating values of \((\Delta H(_1) + \Delta H(_2))\) and sublimation enthalpies, which are affected by ionization energies and the stability of the formed ions.

Answer 4

Transition metals exhibit variable oxidation states, typically differing by +1, while non-transition metals show variations of +2. This difference stems from the participation of d-orbitals in transition metals, enabling a broader range of oxidation states.

Answer 5

Cr\(^{2+}\) exhibits strong reducing behavior due to its conversion to Cr\(^{3+}\), which possesses a more stable half-filled t\(_2\)g electron configuration. Conversely, Mn\(^{3+}\) is a strong oxidizing agent because it transforms into Mn\(^{2+}\), characterized by a more stable half-filled d\(^5\) configuration. These stable configurations drive Cr\(^{2+}\) to readily donate electrons and Mn\(^{3+}\) to readily accept electrons.

Answer 6

The ionic equation is: \[ 2MnO_4^- + H_2O + I^- \rightarrow 2MnO_2 + 2OH^- + IO_3^- \]