Why is mercury so dense?

Why is mercury so dense?

Because the molar mass is large;
We can look at this problem from the perspective of gas molecules
For gas molecules, the molar mass is directly proportional to the density, and the ratio is a constant. That is to say, the volume of 1mol gas is the same. If the molecular weight is large, the density will be large;
For liquid, although the distance between atoms becomes smaller, so that the atomic radius needs to be considered, it is still irrelevant. For liquid, the basic rule is that the larger the molecular weight is, the higher the density is;
It is also related to some intermolecular forces;