Properties of Lanthanum
Lanthanum is a silvery-white solid at room temperature. It has a melting point of 920 degrees Celsius (1,688 degrees Fahrenheit) and a boiling point of 3,464 degrees Celsius (6,267 degrees Fahrenheit). The atomic radius in picometers is 195pm and the element has a density of 6.146 g/cc. It is a poor conductor, but is very ductile when it comes to malleability. It rates a 2.5 on the Mohs Hardness Scale. In other words, it is rated to be very soft; soft enough to be cut with a knife. Concerning the chemical side of lanthanum's list of properties, it is very flammable and the most reactive of the rare earth metals. Lanthanum oxidizes when exposed to air, and reacts directly with carbon, nitrogen, boron, selenium, silicon, phosphorus, sulfur, and halogens.
Lanthanum has an atomic number of 57 on the Periodic Table. Therefore, a lanthanum atom consists of 57 protons and 57 electrons. Lanthanum has a mass number of 139 and holds 82 neutrons. If you wanted to find this element on the Periodic Table, it would be found in Period 6, in the Lanthanides, otherwise known as the rare earth metals.
The element Lanthanum was discovered January 1839 in Karolinska Institute, Stockholm. It was discovered when Carl Gustav Mosander searched for impurities within a sample of cerium and found La2O3 through chemical treatment. He named the compound lanthana.
Lanthanum is used to make carbon lights for lighting and projector lights in motion pictures. It makes up 25% of Misch metal, a material used to make flints for lighters. In fact, the high reactivity is a crucial component in creating sparks as a special effect in movies. The compound lanthana, or La2O3, is used to make camera lense glass and other special glasses. Lanthanum only has two stable isotopes, La138 and La139, yet none of them have any known use.
Lanthanum is from the Greek word Lanthaneia, meaning "to lie hidden" or "to escape notice".
- Gray, Theodore W. (2008). The Photographic Card Deck of the Elements.
- Gray, Theodore W. (2009). The Elements: A visual exploration of every known atom in the universe. New York: Black Dog & Leventhal Publishers, Inc.