Mercury is the only metal liquid in the room temperature. It behaves that way thanks to the relativistic effects i.e. things that happen when electrons move close to the speed of light.
Mercury’s place in periodic table is such that these effects are taken to the extreme due to its electron configuration.
Mercury’s place in periodic table is such that these effects are taken to the extreme due to its electron configuration.
Here is nice popular article with references that explain more: https://www.chemistryworld.com/news/relativity-behind-mercur...