Question

Transition elements are d-block elements and inner transition elements are f-block elements.

i) Write any two properties of transition elements.

ii) Name a transition metal compound and write one use of it.

iii) What is Lanthanoid Contraction?

iv) Write any two consequences of Lanthanoid Contraction.

Answer 1

i) Transition elements are metals, have high melting points and high enthalpy of atomisation, exhibit variable oxidation states, show paramagnetism, form coloured compounds, form complex compounds, show catalytic properties, form interstitial compounds, form alloys etc. (any two properties)

ii) Fe to makes steal

iii) The overall decrease in atomic and ionic radii from lanthanum to lutetium, caused by the poor shielding of one 4f electron by another is called lanthanoid contraction.
iv)

1. The atomic radii of second row of transition elements are almost similar to those of third row of transition elements.

2. The almost identical radii of Zr (160 pm) and Hf (159 pm).

3. All the lanthanoids have quite similar properties and due to this they are difficult to be separated.

4. The basic strength of hydroxides decreases from La(OH)₃ to Lu(OH)₃ due to decrease in size of M³⁺ ions and consequent increase in the covalent character of M – OH bond.