Mercury

 The chemical element mercury has the atomic number 80 and the symbol Hg. It was once known as hydrargyrum and goes by the moniker quicksilver. The only other metallic element that is known to be liquid under normal circumstances for temperature and pressure is the halogen bromine, while metals like caesium, gallium, and rubidium melt slightly above room temperature. Mercury is a heavy, silvery d-block element.

The primary form of mercury found in global deposits is cinnabar. Grinding either synthetic mercuric sulfide or natural cinnabar yields the red color vermilion.

Mercury is used in a variety of devices, including thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps, and others. However, due to worries about the element's toxicity, mercury thermometers and sphygmomanometers have been largely phased out in clinical settings in favor of substitutes like alcohol- or galinstan-filled glass thermometers and thermistor- or Likewise, mercury sphygmomanometers have been replaced with mechanical pressure gauges and electrical strain gauge sensors.

In certain places, amalgam is still used for dental repair, and mercury is still used in scientific research applications. Additionally, fluorescent lighting uses it. Short-wave ultraviolet light is created when electricity is delivered through mercury vapor in a fluorescent lamp. This light then causes the phosphor in the tube to glow, producing visible light.