Question

Name the following:
A metal which is a liquid at room temperature.

Answer 1

Hint: Liquid metal consists of alloys with very low melting point which form of a eutectic that is liquid at room temperature. One such example of liquid metal is an element having an atomic number 80.

Step by step answer:
The electrons in a mercury atom are bound more tightly than usual to the nucleus. While mercury is only liquid metal at room temperature the elements gallium, cesium and rubidium melt under slightly warmer conditions.
Mercury is a liquid metal because it has a completely filled 6s orbital. Mercury has an unique electronic configuration which makes the outer orbital close to the nucleus. An f shell poorly screens the nuclear charge that stabilizes the 6s orbital. Thus, it is impossible to form any bond with other elements.

Additional Information:
Mercury is used in fluorescent lamps, thermometers, float valves, dental amalgams, in medicine, for the production of other chemicals, and to make liquid mirrors.
Mercury is 13.5 times denser than water. Its liquid and gaseous forms are highly poisonous, when inhaled or ingested. Mercury can accumulate in the body slowly degrading the membranes of important organs like the brain, nervous system, kidneys or liver.
Mercury has a melting point of -38.9 degree Celsius.
Mercury has a boiling point of 356.7 degree Celsius.
Droplets of liquid mercury are shiny and silver-white with a high surface tension, appearing rounded when on flat surfaces.

Note: Mercury is very bad at sharing electrons unlike most metal atoms which readily share valence electrons with other atoms. The electrons in a mercury atom are bound more tightly than usual to the nucleus.