Zinc is a relatively common metal with the atomic number 30 and has the symbol Zn in the table of chemical elements. It is a basic element, being the first of the 12th group of the table. It can be found in large quantities on Earth and is actually the 24th most common of all elements. The most abundant zinc ore is called sphalerite (zinc sulfide mineral). The ore is froth floated, then burned and purified using electricity. The largest zinc mineral resources are in in Australia, USA and some Asian countries.
This element is classified as a transition metal, alongside mercury, nickel and some others. It is quite common and can be found on almost all continents. This makes it useful in numerous alloys and industrial products, with a wide range of applications. While it is not needed in large quantities, most life forms require zinc in minor doses. It is important in nutrition and can be found in a number of foods, the most common sources of zinc being whole grains and other plant seeds.
In pure form, zinc is a shiny metal with a white or even light blue color. It's not useful in industry when pure because it is very brittle. When heated, it turns very soft and can be shaped with ease. It burns with a blue or green flame and it becomes an extremely reactive metal, forming compounds with many other elements.
The name of zinc probably comes from the German word Zinke, which means tooth, and was given by medieval alchemist Paracelsus. Andreas Sigismund Marggraf, another German chemist, was the first to isolate pure zinc in 1746. By 1800, the research of Italian scientists Alessandro Volta and Luigi Galvani has revealed the important electrochemical properties of the metal.
One of its first industrial uses that remains the most important even today is the process of hot-dip galvanizing that applies a coating of zinc on iron to prevent rust. It is however used in a variety of other roles, from metal alloys like brass to power batteries and castings that don't require a lot of strength. This metal is very reactive and its compounds have many uses. Zinc methyl or zinc diethyl are used in organic labs, zinc chloride is an ingredient in deodorants, zinc pyrithione can prevent dandruff and is included in shampoos, some paints have a content of zinc sulfide, while zinc carbonate and zinc gluconate are part of food supplements.
The importance of zinc in nutrition was ignored for some time but it is considered today to have a considerable role in human health and biology. It is especially important for women, before and after they give birth. The lack of zinc is the cause of many diseases and it is believed that millions of people suffer from it, even in rich nations. Zinc deficiency is extremely harmful for children and causes retardation, poor immunity, diarrhea and late sexual maturity. However, too much zinc is also toxic and leads to poor absorption of copper, ataxia or lethargy.
Zinc is classified as an essential mineral that plays a role in the normal cell functions. About 100 enzymes have zinc in their composition and can't work without it. It is also critical for cellular division, the production of DNA or proteins, faster healing of wounds as well as the immune system. It is needed for our senses like taste or smell and can be especially important in child development, from infancy to adolescence. The human body is unable to store zinc, so we must get it constantly from our food.
Zinc is one of the early metals used by man (especially in India). However, it was unknown in Europe. Only in the 1500s small imports from Asia began to arrive and it was initially very expensive because of its rarity. However, by 1700 European scientists succeeded in obtaining pure zinc. Andreas Marggraf is credited for it, but some sources credit other chemists for its discovery.
Zinc is not very useful in pure form but can be very valuable in alloys. Bronze for example has a content of zinc, which gives it both increased strength and malleability. Zinc oxide stops UV radiation and is a key ingredient of sun protection products. It remains widely used for galvanizing and soldering and can be found in paints, batteries and as an alloy of coins.
The required human intake of zinc is about 11 mg per day. It can be found in numerous foods but the right dosage is important. While a lack of zinc has side effects like digestive problems or baldness, too much of it leads to anemia, stomach pain or other problems.
Unlike other metals, zinc is not toxic even in pure form. However, some of its compounds are dangerous, so it must be handled with care. Free ions of zinc are extremely reactive and are a hazard, especially for people who work with the heated metal and are exposed to its fumes. Protection gear is mandatory when smelting the metal, in order to avoid problems. Excess zinc blocks the absorption of other minerals, which can have severe nutrition consequences. This leads to very nasty health issues, so the excess of zinc must be avoided and treated.