“Mercury’s liquid state results almost entirely from relativistic effects, said Peter Schwerdtfeger, a quantum physicist at Massey University in New Zealand. Toward the bottom of the periodic table, the electrons in the heaviest elements experience such strong attraction to the atomic nucleus that they move close to the speed of light. At this point, they no longer obey the laws of classical physics, and the resulting quantum phenomena — known as relativistic effects — lead to surprising physical properties. How these manifest depends on the element…”
Get near-enough to the north (or south) pole and mercury turns into a solid.
Which is a better thing than when some gets spilled on the floor because it spatters into a thousand droplets that you have to chase around the floor , can’t mop up , can’t vacuum up … and can vaporize more easily and poison you.