How is the variability in oxidation states of transition metals different from that of the p-block elements?

Question

 (a) How is the variability in oxidation states of transition metals different from that of the p-block elements?

(b) Out of Cu⁺ and Cu²⁺, which ion is unstable in aqueous solution and why?

(c) Orange colour of Cr²O₇^2- ion changes to yellow when treated with an alkali. WhY?

Answer 1

(a) In p- block elements the difference in oxidation state is 2 and in transition metals the difference is 1.

(b) In aqueous solution, Cu²⁺ is more stable due to higher hydration energy which compensates to the ionization energy of Cu²⁺→ Cu¹⁺

In aqueous solution, Cu¹⁺ undergoes disproportionation reaction

When an alkali is added to an orange solution of dichromate, a yellow solution is obtained due to the formation of chromate ions.