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Lanthanum Facts

Chemical & Physical Properties


Lanthanum is a soft, ductile, and malleable silvery-white metal.

Lanthanum is a soft, ductile, and malleable silvery-white metal.

Periodic Table of the Elements


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

References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952)

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