Question

I am aware of the fact that d-block elements like zinc, cadmium and mercury have lower melting points than other d-block elements. Also I am aware that these three metals have a fully filled d shell.

How does the fully-filled d orbital help in explaining the reduced melting point? What effect explains mercury being a liquid and zinc and cadmium being solids at room temperatures?

Answer 1

Zinc, cadmium, and mercury have low melting points related to their fully filled d-orbitals, leading to weaker metallic bonds. Mercury is liquid at room temperature due to its low melting point, influenced by relativistic effects and crystal structure.

Step-by-step explanation:

The relatively low melting points of zinc, cadmium, and mercury compared to other d-block elements can largely be attributed to their fully filled d-orbitals. In metals, bonding often involves the delocalization of valence electrons, which contributes to the overall strength of the metallic bond.

With a complete d10 configuration, there is less delocalization of electrons as compared to elements with partially filled d-orbitals, resulting in weaker metallic bonds and lower melting points.

Mercury's liquid state at room temperature is an exception amongst metals, primarily due to its filled d-shell but also because of its low melting point, which is further affected by the combination of relativistic effects on its electrons and low symmetry of interatomic forces in its crystal structure.

Zinc and cadmium, though solid at room temperature, also have lower melting points than most transition metals for similar reasons related to their electronic structures.