Appearance and Characteristics
Harmful effects:
Cerium is considered to be moderately toxic.
Characteristics:
Cerium is a reactive, soft, gray, lustrous metal that is malleable and ductile.
When present in compounds, cerium exists in both the trivalent state (Ce3+, cerous, usually orange-red) and the tetravalent state (Ce4+, ceric , usually colorless). The metal tarnishes in moist air and reacts with water to form cerium hydroxide plus hydrogen gas. Small particles of the metal may ignite if a knife scratches the pure metal surface. It is attacked by alkali solutions and all acids. Cerium has a variable electronic structure: the energy of the inner 4f level is nearly the same as that of the 6s level, allowing variable occupancy of these two levels.
Uses of Cerium
An alloy of cerium and lanthanum, with small amounts of neodymium and praseodymium (misch metal) combined with iron oxide and magnesium oxide is used as the flint in cigarette and gas lighters.
Cerium is used in carbon-arc lighting, especially in the motion picture industry. It is also used in phosphors for color television screens and fluorescent lighting.
Cerium oxide is used as a catalytic converter to reduce carbon monoxide emissions in the exhaust fumes from automobiles. Cerium oxide, as a nanopowder, is added to diesel fuel to reduce sooty fumes and improve engine performance. It is used in the walls of self-cleaning ovens and is also used to polish glass surfaces.
Flammacerium (cerium nitrate-silver sulphadiazine) is a cream to treat and prevent infections in extensive burn wounds. The cerium nitrate component reduces the occurrence of immunosuppression.