Lanthanum

Lanthanum (La)

(From the Greek word lanthanein, to line hidden) Silvery metallic element belonging to group 3 of the periodic table and oft considered to be one of the lanthanoids. Found in some rare-earth minerals. Twenty-five natural isotopes exist. La-139 which is stable, and La-138 which has a half-life of 10^10 to 10^15 years. The other twenty-three isotopes are radioactive. It resembles the lanthanoids chemically. Lanthanum has a low to moderate level of toxicity, and should be handled with care. Discovered in 1839 by C.G. Mosander.
Atomic Number57
Atomic Weight138.90547
Mass Number139
Group3
Period6
Blockd
Protons57 p+
Neutrons82 n0
Electrons57 e-
Lanthan 1-cropflipped.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
195 pm
Atomic Volume
Covalent Radius
180 pm
Metallic Radius
169 pm
Ionic Radius
103.2 pm
Crystal Radius
117.19999999999999 pm
Van der Waals radius
243.00000000000003 pm
Density
6.15 g/cm³
Boiling Point
3,730 K
Melting Point
1,194 K
Electrons per shell2, 8, 18, 18, 9, 2
Electronegativity
1.1
Electrophilicity
0.894990101872 eV/particle
Proton Affinity
1,013 kJ/mol
Electron Affinity
Ionization Potential
Heat of Vaporization
402 kJ/mol
Heat of Fusion
8.5 kJ/mol
Heat of Formation
431 kJ/mol
Molar Heat Capacity
27.11 J/(mol K)
Specific Heat Capacity
0.195 J/(g⋅K)
Thermal Conductivity
13.4 W/(m K)
Gas Basicity
991.9 kJ/mol
Dipole Polarizability
215 a₀
C6 Dispersion Coefficient
Oxidation States2, 3
Color
Silver
Crystal StructureSimple Hexagonal (HEX)
Lattice Constant
3.75 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Xe] 5d1 6s2
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryLanthanides, Lanthanides
CAS GroupIIIA
IUPAC GroupIIIB
Glawe Number32
Mendeleev Number13
Pettifor Number33
Geochemical Classrare earth & related
Goldschmidt Classlitophile
Radioactivity
RadioactiveNo
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
Abundance in Oceans
0.0000034 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe2×10-7%

Isotopes of Lanthanum

Stable Isotopes
138La 139La
Unstable Isotopes
117La 118La 119La 120La 121La 122La 123La 124La 125La 126La 127La 128La 129La 130La 131La 132La 133La 134La 135La 136La 137La 140La 141La 142La 143La 144La 145La 146La 147La 148La 149La 150La 151La 152La 153La 154La 155La

History

Lanthanum was discovered in 1839 by Swedish chemist Carl Gustav Mosander. He partially decomposed a sample of cerium nitrate by heating and treating the resulting salt with dilute nitric acid. From the resulting solution, he obtained a pale brick colored oxide of the new rare earth. Lanthanum was isolated in relatively pure form in 1923. From the Greek word lanthanein, to lie hidden

DiscoverersCarl Mosander
Discovery LocationSweden
Discovery Year1839
Name OriginGreek: lanthanein (to be hidden).
Lanthanum and its compounds are considered to be moderately toxic
Lanthanum is the most reactive of the rare earth metals

Uses

Lanthanum is used in large quantities in batteries for hybrid automobiles. It is also used to make night vision goggles. Small amounts of lanthanum, as an additive, can be used to produce nodular cast iron. Lanthanum carbonate is used to reduce blood levels of phosphate in patients with kidney disease. It is used in the electodes of high-intensity, carbon-arc lights. Also used in the production of high-grade europium metal. Because it gives glass refractive properties, it is used in expensive camera lenses.

Sources

Found with rare earths in monazite and bastnasite. Monazite sand typicall contains 25% lanthanum.