Step 1 : Introduction to the question "What is the only metallic element that is liquid at room temperature?"
Mercury is the only metal that is liquid at room temperature. It also has the lowest melting point and boiling point of any other metal. Mercury is used to make thermometers, barometers and many other scientific instruments. However, mercury is a very toxic element and for safety reasons, consumer use of mercury in thermometers has become less common over the years. The symbol Hg that mercury is known by comes from its Greek name, hydrargyrum, which means "liquid silver" — to reflect its shiny surface.
