Mercury has fascinated people for centuries. Drop a bead of it onto a tabletop and it rolls away like a living thing, pulling itself together into a perfect sphere before flowing back to merge with the rest. This behaviour stems from an exceptionally high surface tension, and it makes mercury almost hypnotically captivating to watch. It was long used in thermometers and barometers, because it expands so evenly as temperature rises.

You rarely see mercury in modern household devices anymore, as safer alternatives have become available.

On the periodic table, mercury appears as Hg, an abbreviation of the old name “hydrargyrum”, which roughly translates as “liquid silver”. That name says it all, really. And then there is a detail that regularly causes confusion at pub quizzes: mercury is not the only element that is liquid at room temperature. Bromine, a non-metal, is too. Two elements on the entire periodic table that exist as liquids at ordinary temperatures. Anyone who knows that has a ready-made follow-up question in their back pocket.