Mercury is classified as a metal. It is distinct from other metals because it is the only metal that is liquid at room temperature.
In the periodic table, metals are typically defined by their ability to conduct electricity and heat, as well as their malleability and ductility. Mercury exhibits all of these characteristics, despite its liquid state at room temperature. This unique property allows it to fit within the metal category.
Mercury has a high density, can form alloys with other metals, and displays properties such as luster and conductivity. While it does have some unique characteristics—being the only metal that is liquid at standard conditions—it still falls under the definition of metals due to its overall properties.
In summary, mercury is unequivocally classified as a metal due to its physical and chemical properties, even though its liquid state sets it apart from most other metals.