[gomess]

Correct me if I am wrong, but to my knowledge the strength of a metallic bond is increases as the number of valence electrons increases. Mercury has a higher number of valence electrons than say Iron, however mercury exists as a liquid at room temperature. Doesn't this imply the intermolecular forces in mercury are weaker than those in iron?

[cheah10]

the basic reason is that, the electronic configuration of mercury is more stable than other metals(which you can see from the fact that all its electron-occupied subshells are completely filled), therefore its valence electrons do not delocalise as many as that of other metal atoms.

From here, can you figure out the reason for why mercury is a liquid but not for other metals now?

[cheah10]

There are some other reasons for it also. You can read about it at http://www.rsc.org/chemistryworld/2013/06/why-mercury-liquid-relativity-evidence

[gomess]

Is it something to do with the fact that filled d subshells are more stable than s subshells? Interesting post btw.