Question:
Why do transition elements show variable oxidation states?
Solution:
- Transition elements show variable state oxidation in their compounds because there is a very small energy difference between (n-1)d and ns orbitals. As a result, electrons of (n-1)d orbitals as well as ns-orbitals take part in bond formation.
- Mn (Z=25) has the maximum number of unpaired electrons present in the d-subshell so it shows maximum oxidation states (+7)
- Sc only exhibits a +3 oxidation state in this series.
- The lanthanide contraction, i.e., the reduction in size of the Ln3+ ion from La3+ (103 pm) to Lu3+ (86.1 pm), is often explained by the poor shielding of the 5s and 5p electrons by the 4f electrons.
An alloy is a solid solution of two or more elements in a metallic matrix. It can either be a partial solid solution or a complete solid solution. Alloys are usually found to possess different physical properties than those of the component elements. An important alloy of lanthanoids is Mischmetal. It contains lanthanoids (94%).