Posted in Science & Nature

Silver

Historically, silver has been associated with cleansing, healing, the moon and warding off evil. For example, it is said that some monsters such as werewolves would only die if it is shot by a silver bullet. The Greek goddess of hunting and the moon, Artemis, carries a silver bow. Although it is always seconded to gold when it comes to precious metals, silver is a fascinating metal.

It is the most reflective metal on Earth and has the highest conductivity for heat and electricity. It is ductile and malleable, making it a good choice of metal for making coins, jewellery and silverware (hence the name). Because of how reflective it is, it is also used in solar panels and special mirrors, such as those in telescopes.

Another useful characteristic of silver is its chemical reactivity. Thanks to this property, silver forms many different compounds with varying applications. Silver halides are photosensitive and turn dark when they are exposed to light. This is the basis of film photography, where the light shone on a film coated with silver halides leaves a photographic imprint. Silver oxides are sometimes used in batteries and silver/mercury alloys are used for dental fillings.

Silver also plays a role in medicine. Silver ions have been shown to inactivate bacteria such as E. coli, making silver nanoparticles a useful antiseptic that can be impregnated into different materials such as wound dressings. Silver nitrate sticks are used in emergency departments as applying it to a bleeding vessel in the nose will release nitric acid, which cauterises (burns off) the vessel to stop a nosebleed. In medieval Korea, silver spoons were used to test if a food has been poisoned with arsenic, as arsenic reacts with silver to form a black tarnish. If a person has too much silver build-up in their body, they can develop argyria (silver poisoning), which turns the skin an eerie bluish-grey colour.

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