How does this make mercury a liquid at STP?

[hmunster]

Thinking back to my undergraduate years in Chemistry 101, it always struck me as strange that mercury, a transition metal, was liquid at room temperature. When I asked the professor about it, he said the explanation was by no means simple and involved both the electronic configuration of mercury and relativity as it related to the outermost electrons of that element. Seems they orbit at such a significant fraction of c that they weigh more as a consequence. But how does this make mercury a liquid at STP? I still can't recall the explanation.

 

[SteamKing]

IDK about the relativity part, but the electron configuration of mercury is one part of the explanation of why it is liquid at room temp. (bromine is the other element with this property, and several other metals have similarly low melting points):

http://en.wikipedia.org/wiki/Mercury_(element)

See the section on 'Physical Properties'.