Titanium Titanium Titanium is a chemical element with symbol Ti and atomic number 22. It is a lustrous transition metal with a silver color, low density, and high strength. Titanium is resistant to corrosion in sea water, aqua regia, and chlorine. Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, and was named by Martin Heinrich Klaproth after 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, water bodies, rocks,
Rare-earth element that fall in between are typically referred to as the middle rare-earth elements (MREE). Commonly, rare-earth elements with atomic numbers 57 to 61 are classified as light and those with atomic numbers greater than 62 (corresponding to europium) are classified as heavy-rare earth elements. Increasing atomic numbers between light and heavy rare-earth elements and decreasing atomic radii throughout the series causes chemical variations. Europium is exempt of this classification as it has two valence states: Eu and Eu. Yttrium is grouped as heavy rare-earth element due to chemical similarities. Rare-earth elements, except scandium, are heavier than iron and thus are