Szerkesztő:BélaBéla/Noteć

A titán a periódusos rendszer egy kémiai eleme. Vegyjele Ti, rendszáma 22, nyelvújításkori magyar neve kemeny. Az átmenetifémek közé tartozik. A titán igen kis sűrűségű, nagy szilárdságú és erősen korrózióálló fém, ellenáll a királyvíznek és a klórnak is.

A Titánt William Gregor fedezte fel 1791-ben, nevét pedig Martin Heinrich Klaprothtól kapta a görög mitológiai titánok után. Az elem számos ásványban megtalálható, legjelentősebbek ezek közül a rutil és az ilmenit, melyek széles körben megtalálhatók a földkéregben és a litoszférában.

Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791 and named by Martin Heinrich Klaproth for the Titans of Greek mythology. The element occurs within a number of mineral deposits, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere, and it is found in almost all living things, rocks, water bodies, and soils. The metal is extracted from its principal mineral ores via the Kroll process or the Hunter process. Its most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride (TiCl₄), a component of smoke screens and catalysts; and titanium trichloride (TiCl₃), which is used as a catalyst in the production of polypropylene.

Titanium can be alloyed with iron, aluminium, vanadium, and molybdenum, among other elements, to produce strong, lightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial process (chemicals and petro-chemicals, desalination plants, pulp, and paper), automotive, agri-food, medical prostheses, orthopedic implants, dental and endodontic instruments and files, dental implants, sporting goods, jewelry, mobile phones, and other applications.

The two most useful properties of the metal are corrosion resistance and the highest strength-to-density ratio of any metallic element. In its unalloyed condition, titanium is as strong as some steels, but less dense. There are two allotropic forms and five naturally occurring isotopes of this element, ⁴⁶Ti through ⁵⁰Ti, with ⁴⁸Ti being the most abundant (73.8%). Although they have the same number of valence electrons and are in the same group in the periodic table, titanium and zirconium differ in many chemical and physical properties.