The d- and f-Block Elements short notes

Configuration

• The general d-block configuration is (n − 1)d¹⁻¹⁰ ns¹⁻².
• Cr is 3d⁵4s¹, and Cu is 3d¹⁰4s¹, for extra stability.
• Zn, Cd and Hg aren't regarded as transition metals, since their d orbitals are full in the ground state and common oxidation states.

Properties

• They have high melting points and high enthalpies of atomisation, from strong metallic bonding. Mn is unusually low, and Zn lowest.
• They show variable oxidation states, since the (n − 1)d and ns electrons have similar energies. Mn has the most, up to +7.
• Coloured ions come from d-d transitions, which need unpaired d electrons.
• Magnetic moment rises with the number of unpaired electrons.
• They form complexes and alloys, and act as catalysts.
• Interstitial compounds form when small atoms such as C and N enter the metal lattice.

Magnetic moment

Spin-only formula

$\displaystyle \mu = \sqrt{n(n + 2)}\ \text{BM}$

n is the number of unpaired electrons.

Important compounds

• K₂Cr₂O₇ is orange, and an oxidising agent in acid. It's made from chromite ore.
• KMnO₄ is purple, and made from pyrolusite (MnO₂). It's a strong oxidising agent.
• Chromate and dichromate change into each other with pH.

f-block

• Lanthanoids mostly show +3.
• Lanthanoid contraction: the radius falls steadily, because 4f electrons shield poorly.
• As a result, Zr and Hf have nearly the same size.
• Actinoids are all radioactive, and show a wider range of oxidation states than lanthanoids.