Mercury Hg2+2 Ion: Why Does It Form?

[Cesium]

Mercury can form Hg2+2 and Hg+2 ions. Why does mercury form Hg2+2? Are there any other "diatomic ions" like this? I assume this has to do with atomic size, but why don't zinc and cadmium behave like this? They only form Zn+2 and Cd+2.

 

[chem_tr]

Hg⁺ atom has sp hybrid orbital, so it likes to bond with additional Hg⁺ ion to form a Hg₂²⁺ ion. Copper(I) ions are said to form such bonding, but I am not sure about this. Also some atoms in which organometallic bonding principles are present (like Mn₂(CO)₁₀) has Mn-Mn bonding to reach a stable noble gas configuration.

 

[ravenprp]

The formation of Hg2+2 ions in mercury is due to its unique electronic configuration and the presence of a filled d-subshell. Mercury has a relatively low ionization energy, making it easier for the two electrons in its outermost s-orbital to be removed, resulting in the formation of Hg2+2 ions. Additionally, the filled d-subshell provides stability to the Hg2+2 ion, making it more favorable for mercury to form this ion rather than a single Hg+2 ion.

There are other diatomic ions similar to Hg2+2, such as Cu2+2 and Pt2+2, which also have a filled d-subshell and form stable diatomic ions. However, the formation of these diatomic ions is not as common as Hg2+2 and is dependent on factors such as electronegativity and ionization energy.

As for why zinc and cadmium do not form diatomic ions like Hg2+2, it is due to their electronic configurations and ionization energies. Zinc has a filled d-subshell and a relatively high ionization energy, making it less likely to form diatomic ions. Cadmium, on the other hand, has a partially filled d-subshell and a lower ionization energy, making it more likely to form Cd+2 ions rather than a diatomic ion.

In conclusion, the formation of Hg2+2 ions in mercury is due to its unique electronic configuration and the stability provided by its filled d-subshell. While there are other diatomic ions like Hg2+2, their formation is dependent on various factors and is not as common as Hg2+2. The lack of diatomic ion formation in zinc and cadmium can be attributed to their different electronic configurations and ionization energies.