What is Cerium?
'''Cerium''' is a chemical [[Chemical element|element]] with an [[atomic number]] of 58. This means that the [[Nucleus (physics)|nucleus]] of cerium has 58 [[protons]] in it. The [[atomic mass]] of cerium is 140.12. The [[chemical symbol]] of cerium is '''Ce''' and it is a member of the [[lanthanide]] group. == Properties == Cerium is a grey, shiny or [[lustrous]] [[metal]]. At [[room temperature]] cerium is a [[solid]]. It melts and becomes a [[liquid]] at 798<sup>o</sup>C and boils and becomes a [[gas]] at 3424<sup>o</sup>C. It burns in air to form a compound with one cerium atom and two [[oxygen]] atoms. 0.0046% of the Earth's [[Crust (geology)|crust]] is cerium which means that it is quite common - more common than [[Tin]] and [[Lead]] and nearly as common as [[zinc]] == Discovery == Cerium was first found in [[Sweden]] in 1803 by Berzelius and Hisinger and Klaproth in [[Germany]]. Because it is very reactive, it was not purified until 1875 in [[Washington DC]]. Cerium was named after the [[asteroid]] or minor planet [[Ceres_(dwarf_planet)|Ceres]] which was first seen two years earlier in 1801. == Uses == Cerium is not often used as a metal since it quickly reacts with the air and tarnishes. Its most common use is as the 'flint' in a lighter, because it easily produces a spark when it is struck with another metal. Cerium is sometimes used in [[alloy]]s because it often makes the alloy more heat resistant. Cerium is also used in special [[glass]], ceramics and self-cleaning ovens. == Oxidation == Cerium reacts in two ways to produce '''cerous''' [[Chemical compound|compound]]s or [[salt]]s and '''ceric''' compounds. Cerous salts have an [[oxidation]] number of 3 and ceric salts have an oxidation of 4. == Isotopes == Cerium has many [[isotopes]]. Four of them are (observationally) stable, and are found in nature instead of having to be made, * Cerium-136 which has 58 protons and 78 neutrons in its nucleus * Cerium-138 which has 58 protons and 80 neutrons * Cerium-140 which has 58 protons and 82 neutrons *