Cerium is a rare earth element which has a number of uses, especially in metallurgy. Consumers generally interact with the element in the form of a product component, and several isotopes and cerium compounds are also used in manufacturing. This element has been deemed mildly toxic, and it can be dangerous under certain conditions; people who work with cerium are generally trained in how to safely handle it, and how to recognize markers of dangerous levels of exposure.
In appearance, cerium can look a great deal like lead. It is iron-gray in color with a faint luster and it is highly malleable. Cerium also has three other allotropic states, meaning that it takes different pure forms depending on conditions like pressure and temperature. It is identified with the symbol Ce on the periodic table of elements, and it has an atomic number of 58. In addition to being considered a rare earth element, cerium is also a lanthanoid, sharing characteristics like high reactivity, including flammability, along with high boiling and melting points, with a group of other elements.
The discovery of cerium is credited separately to J.J. Berzelius and Wilhelm Hisinger in Sweden and M.H. Klaproth in Germany in 1803. Berzelius named the element after the asteroid Ceres, which was first observed in 1801. However, it took another 72 years to successfully isolate the element, since the technology to do so did not exist when cerium was first identified. Cerium was also discovered to be a rather abundant rare earth element, appearing in many minerals and ores.
Commercially, cerium is used in metalworking, nuclear applications, glass, and enameling. It is also commonly used in the flints for lighters, since pure cerium will catch fire if it is scratched. The element can be extracted from the minerals which is naturally appears in, along with the ores that it tends to mingle with. Cerium also appears to be a byproduct of nuclear fission. Compounds and oxides of cerium are used in chemistry and cleaning products, among other things.
The reactivity of cerium can make it dangerous to handle, especially since it emits toxic fumes when it is set on fire. The element also reacts with water, and it has been known to cause itchy skin, lesions, and heat sensitivity. It can also sometimes contain traces of radioactive material if it has not been fully purified, which can pose a risk to people to handle cerium.