Science, Tech, Math › Science Lanthanum Facts - La Element Chemical & Physical Properties Share Flipboard Email Print Lanthanum is atomic number 57. Malachy120 / Getty Images Science Chemistry Periodic Table Basics Chemical Laws Molecules Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated August 02, 2019 Lanthanum is element number 57 with element symbol La. It is a soft, silver-colored, ductile metal known as the starting element for the lanthanide series. It is a rare earth element that usually displays the oxidation number of +3. While lanthanum serves no known biological role in humans and other animals, it is an essential element for some types of bacteria. Here is a collection of La element facts, along with the atomic data for lanthanum. Fast Facts: Lanthanum Element Name: LanthanumElement Symbol: LaAtomic Number: 57Appearance: Silvery white solid metalAtomic Weight: 138.905Group: Group 3Period: Period 6Block: d-block or f-blockElectron Configuration: [Xe] 5d1 6s2 Interesting Lanthanum Facts Lanthanum is a metal so soft it can be cut with a butter knife. It is highly malleable and ductile. Although the freshly cut metal is bright silver, it rapidly oxidizes or tarnishes in air.Lanthanum was discovered by Carl Mosander in 1839 in the mineral cerite. Mosander was a student of Swedish chemist Berzelius, who had discovered cerium in cerite in 1803. Mosander had suspected ceria contained more rare earth elements besides cerium. Axel Erdmann independently discovered lanthanum the same year as Mosander from a Norwegian mineral Erdmann named mosandrite, in honor of Mosander. Pure lanthanum metal was not produced until 1923 by H. Kremers and R. Stevens.Berzelius suggested the named Lanthana for the new element, which comes from the Greek word "lanthano", meaning "to be hidden".Natural lanthanum is a mixture of two isotopes. La-139 is stable, while La-138 is radioactive. At least 38 isotopes of the element have been produced. Lanthanum is one of the most reactive of the rare earth elements. Its uses are somewhat limited by how readily it oxidizes. It is the strongest base of there found in hybrid cars. About 10 kg of lanthanum are needed to make one Toyota Prius ba trivalent lanthanides.Lanthanum is used in nickel-metal hydride batteries, which attery! Lanthanum compounds may be added to pool produces to lower levels of phosphates, reducing algae growth. Lanthanum is also used as a petroleum cracking catalyst, as a steel additive, to make nodular cast iron, to make infrared absorbing glass and night vision goggles, and to make high-end camera and telescope lenses. Lanthanum oxide has a low dispersion and high refractive index.Lanthanum has no known function in human or animal nutrition. Because it is so reactive, it is considered moderately toxic. Lanthanum carbonate is used to reduce blood phosphate levels in patients with kidney disease.Like most rare earth, lanthanum is not really all that rare, just hard to isolate. Lanthanum is present at an abundance of about 32 parts per million in the Earth's crust. Lanthanum is a soft, ductile silvery metal. Jurii Lanthanum Atomic Data Element Name: Lanthanum Atomic Number: 57 Symbol: La Atomic Weight: 138.9055 Discovery: Mosander 1839 Name Origin: From the Greek word lanthaneis (to lie hidden) Electron Configuration: [Xe] 5d1 6s2 Group: lanthanide Density @ 293 K: 6.7 g/cm3 Atomic Volume: 20.73 cm3/mol Melting Point: 1193.2 K Boiling Point: 3693 K Heat of Fusion: 6.20 kJ/mol Heat of Vaporization: 414.0 kJ/mol 1st Ionization Energy: 538.1 kJ/mole 2nd Ionization Energy: 1067 kJ/mole 3rd ionization Energy: 1850 kJ/mole Electron Affinity: 50 kJ/mole Electronegativity: 1.1 Specific Heat: 0.19 J/gK Heat Atomization: 423 kJ/mole atoms Shells: 2,8,18,18,9,2 Minimum Oxidation Number: 0 Maximum Oxidation Number: 3 Structure: hexagonal Color: silvery-white Uses: lighter flints, camera lenses, cathode ray tubes Hardness: soft, malleable, ductile Isotopes (half-life): Natural lanthanum is a mix of two isotopes, though more isotopes now exist. La-134 (6.5 minutes), La-137 (6000.0 years), La-138 (1.05E10 years), La-139 (stable), La-140 (1.67 days), La-141 (3.9 hours), La-142 (1.54 minutes) Atomic Radius: 187 pm Ionic Radius (3+ ion): 117.2 pm Thermal Conductivity: 13.4 J/m-sec-deg Electrical Conductivity: 14.2 1/mohm-cm Polarizability: 31.1 A^3 Source: monazite (phosphate), bastnaesite Sources Emsley, John (2011). Nature's building blocks: An A-Z Guide to the Elements. Oxford University Press. ISBN 978-0-19-960563-7.Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.Hammond, C. R. (2004). The Elements, in Handbook of Chemistry and Physics (81st ed.). CRC press. ISBN 978-0-8493-0485-9.Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. ISBN 0-8493-0464-4.