Question

Is mercury(I) chloride ionic or covalent? If I look here, I see arguments either way. The article doesn't mention anything about a cation or an anion.

Some might think there's two mercury ions each 1+ but it seems to me that's not the case, as the article mentions that the chemical is also known as mercurous chloride. And I see there is such a thing as a mercurious ion, which I understand to be a polyatomic ion with charge of 2+, so that would suggest it's an ionic compound.

This Wikipedia article also mentions that it's Also known as the mineral calomel and it says calomel is a salt mercury salts (such as calomel). So that indicates to me that it's an ionic compound.

But the article on mercury(I) chloride also says Hg2Cl2 is a linear molecule. Well, that suggests it's a covalent compound.

I've also heard that it has a relatively low sublimation point which also implies molecular.

The Wikipedia page also mentions the Hg–Cl bond length in the linear Hg2Cl2 unit is 243 pm

I suppose that might suggest covalent, because as I understand it, bond length is normally mentioned for covalent bonds rather than ionic bonds.. Though with ionic bonds the concept of bond length could apply though i've heard it's usually called interionic distance.

Looking at the pictures, it has this one.

And I understand that that style of diagram is usually used for ionic compounds. It shows a unit cell (which seems to show maybe linear molecules).

And as I understand it, a unit cell could apply not just to an ionic crystal, but to a molecular crystal or a network covalent crystal. So I'm really confused as to what the structure is. I can't tell whether it's ionic or whether it's covalent molecules?

Answer 1

Mercury(I) chloride, also known as mercurous chloride or calomel, is an ionic compound.

Step-by-step explanation:

Mercury(I) chloride, also known as mercurous chloride or calomel, is an ionic compound.

Although there is some confusion due to its linear structure and low sublimation point, the fact that it is classified as a salt and its formula Hg2Cl2 suggests it is an ionic compound.

Additionally, the compound contains the polyatomic ion mercurous ion (Hg22+), which further supports its ionic nature.