The d- and f- Block Elements

Ranges of the given series: 3d, 4d, 5d, 6d, 4f, 5f

3d (Sc -Zn)
4d (Y-Cd)
5d (La, Hf - Hg)
6d (Ac, Rf - Rg, Cn) Cn also known as Uub
4f (Ce - Lu)
5f (Th - Lr)

“All transition elements are d block elements, but all d block elements are not transition elements”. True or False?
If False, what are the exceptions?

False.
Exceptions include Zinc (Zn), Cadmium (Cd), Mercury (Hg), Copernicium (Cn).
[due to fully d10 config in ground state as well as most common ox state]

Why does the general electronic config of d block elements have multiple exceptions? What are the exceptions + their electronic config.

Due to very little energy difference between (n-1)d and ns orbitals, generalisation has a lot of exceptions.
Pd → 4d¹⁰ 5s⁰
Cr → 3d⁵ 4s¹
Cu → 3d¹⁰ 4s¹

High enthalpy of atomisation.

very high boiling point.
noble in reactions
4d and 5d have greater enthaply of atomisation (accounts for occurance of frequent metal-metal bonding in heavy transition metals)

significant increase in density range

Ti (22) to Cu (29)

lanthanoid contraction

decrease in atomic radii due to poor shielding of 4f electrons. 4f orbital needs to get filled before 5d orbital.

4f-4f e shielding < 5d-5d e shielding

Why do transition elements exhibit higher enthalpies of atomisation?

Large number of unpaired electrons → stronger interatomic interaction → stronger bonding between atoms → higher enthalpy of atomisation

Three terms responsible for the value of IE?

→ attraction of each electron towards nucleus
→ repulsion between electrons
→ exchange energy

Exchange energy

→ Responsible for stabilisation of energy state
→ proportional to total number of possible pairs of parallel spins in degenerate orbitals
→ loss of exchange energy increases stability
[as stability increases, ionisation becomes difficult]

high IE₃

Ni<Cu<Zn