The only metal that is liquid at room temperature is mercury (Hg). It is unique among metals for its low melting point of approximately -38.83 degrees Celsius (-37.89 degrees Fahrenheit). Mercury is often used in thermometers, barometers, and various scientific instruments due to its ability to expand and contract predictably with temperature changes. However, it is also known for its toxic properties, and exposure to mercury can lead to serious health risks. As a result, the use and handling of mercury are closely regulated in many countries, particularly in consumer products.