Mercury is a chemical element with the symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum (from Greek “hydr-” water and “argyros” silver)
Mercury is remarkable because it is the only metal that is liquid at room temperature. It is a dense, lustrous grey metal. Mercury is extremely rare in the Earth’s crust and in the wild, it typically is concentrated near volcanically active areas, either as the pure metal or in a number of minerals.
Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element’s toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favour of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments.
The reason mercury was so popular is because it readily forms stable amalgams with a number of other metals, particularly silver and gold, making them workable at lower temperatures, and these amalgams have been the source of many instances of mercury poisoning.
Biologists are quite interested in mercury because it is highly toxic to life, causing both acute and chronic poisoning. Mercury can be absorbed through the skin and mucous membranes and mercury vapors can be inhaled. Mercury is concentrated in the body over the lifetime of the individual, and it also becomes more concentrated when one animal eats another, which is how it moves up the food chain. This is the reason why the flesh of tuna, a long-lived apex predator in the oceans, contain such high levels of mercury.
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