Zinc is a metallic chemical element with the symbol Zn and atomic number 30. In non-scientific context, it is also known as spelter.
In appearance, zinc is a blue-gret metal. It is moderately reactive and tarnishes easily if exposed to air due to a chemical reaction with the water vapour in air to produce zinc hydroxide. It also burns in oxygen wth a bright bluish-green flame, giving off fumesof zinc oxide.
Zinc, as a metal, reacts with dilute acids to release hydrogen gas.
Zinc is primarily used to galvanise steel in order to prevent corrosion. Zinc coatings prevent corrosion of the protected metal by forming a physical barrier, and by acting as a sacrificial anode if this barrier is damaged. This is possible due to the higher reactivity of zinc as compared to iron. When exposed to the atmosphere, zinc reacts with oxygen to form zinc oxide, which further reacts with water molecules in the air to form zinc hydroxide. Finally zinc hydroxide reacts with carbon dioxide in the atmosphere to yield a thin, impermeable, tenacious and quite insoluble dull grey layer of zinc carbonate which adheres extremely well to the underlying zinc, so protecting it from further corrosion, in a way similar to the protection afforded to aluminium and stainless steels by their oxide layers.
Zinc is also used in the production of alloys and is widely-used in die-casting, particularly in the automobile industry. Because zinc is generally non-toxic, it is used in contemporary pipe organ building as a substitute for the classic lead/tin alloy in pipes sounding the lowest (pedal) tones, as it is tonally almost indistinguishable from lead/tin at those pitches, and has the added advantages of being much more economical and lighter in weight.
Zinc is an essential trace element for humans, animals and plants. It is vital for many biological functions and plays a crucial role in more than 300 enzymes in the human body. The adult body contains about 2-3 grams of zinc. Zinc is found in all parts of the body: it is in organs, tissues, bones, fluids and cells. Muscles and bones contain most of the body's zinc (90%). Particularly high concentrations of zinc are in the prostate gland and semen.
Zinc metal is included in most single tablet over-the-counter daily vitamin and mineral supplements. It is believed to possess anti-oxidant properties, which protect against premature aging of the skin and muscles of the body. In larger amounts, taken as zinc alone in other proprietaries, it is believed by some to speed up the healing process after an injury. Preparations include zinc acetate and zinc gluconate.