Appearance and Characteristics
Harmful effects:
Mercury and most of its compounds are highly toxic. The pure metal is absorbed easily by inhalation, ingestion or through the skin. It is also a chronic pollutant and mercury concentrates in animal/fish tissues in increasing amounts up the food chain.
Characteristics:
Mercury is a dense, silvery-white, poisonous metal with a mirror-like appearance. It is the only common metal that is liquid at room temperature. Mercury evaporates slowly at room temperature. Others metals that are liquid near room temperature are gallium, francium and cesium. The metal is relatively stable in dry air, but in moist air tarnishes slowly to form a gray oxide coating. Mercury has high surface tension and, when spilled, breaks up into tiny beads. Mercury readily forms alloys (called amalgams) with other metals, such as silver, gold and tin. As it does not amalgamate with iron, mercury is often stored in iron containers.
Uses of Mercury
Mercury is used in barometers and manometers (instruments for measuring the pressure of gases and liquids), because of its high density. The metal also has a high rate of nearly linear thermal expansion, so it is used extensively in thermometers. Its ease in amalgamating with metals is made use of in extracting gold, silver, and platinum from their ores. Mercury is widely used in making advertising signs, mercury switches and other electrical apparatus. It is also used in mercury-vapor lamps (which emit light rich in ultraviolet radiation). These lamps are typically used for street lighting, as sun lamps, and as UV lights (black lights). Various compounds of mercury are used in medicine, dentistry, cosmetics (mascara) and also in agriculture to make fungicides.