L

Lanthanum

IUPAC: Lanthanum

La Elements CAS 7439-91-0
Quick Reference
Formula / NotationLa
CAS Number7439-91-0
Molecular Weight138.91
Melting Point920.0
Boiling Point3464.0
Density6.14
SolubilityInsoluble in water (reacts slowly)
AppearanceSoft, silvery-white metal, tarnishes in air
Also Known AsLa, lanthanum metal
CategoryElements

What is Lanthanum?

Lanthanum is a soft, silvery-white rare earth metal, atomic number 57, and the first element of the lanthanide series. Highly reactive - tarnishes in air and reacts with water. La2O3 is used in high-refractive-index optical glasses.

Formula & Notation

La

IUPAC Name: Lanthanum

Other Names / Synonyms: La, lanthanum metal

Properties & Characteristics

Atomic number: 57. Atomic mass: 138.91 g/mol. Period 6, f-block (lanthanide). Melting point: 920 C. Boiling point: 3464 C. Density: 6.14 g/cm3. Electronegativity: 1.10. Oxidation state: +3. Two stable isotopes: La-138 (trace, radioactive), La-139 (99.9%).

Physical Data

PropertyValue
Melting Point920.0
Boiling Point3464.0
Density6.14
Molecular Weight138.91
SolubilityInsoluble in water (reacts slowly)
AppearanceSoft, silvery-white metal, tarnishes in air

Uses & Applications

Optical glass (La2O3 for high-refractive-index lenses and camera optics). NiMH battery negative electrode (La-Ni5 alloy). FCC catalysts in petroleum refining. Lanthanum carbonate for treating hyperphosphatemia. Lighter flints (misch metal contains La).

Safety Information

Lanthanum metal and compounds: mildly toxic. Irritant to skin, eyes, respiratory tract. Lanthanum dust combustible. Soluble La compounds: moderate toxicity if ingested. Handle with standard precautions. Limited occupational exposure data.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Lanthanum
Formula La
CAS Number 7439-91-0
Molecular Weight 138.91
Category Elements
Synonyms La, lanthanum metal

Frequently Asked Questions

Lanthanum is a soft, silvery-white rare earth metal, atomic number 57, and the first element of the lanthanide series. Highly reactive - tarnishes in air and reacts with water. La2O3 is used in high-refractive-index optical glasses.

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