The name is derived from the Greek word ‘lanthanein’, meaning: lying hidden. It was discovered in 1839. Its chemical symbol is La.
It is highly reactive and easily oxidises when exposed to the air. It is used in very expensive camera lenses because of its special refraction properties.
The lanthanides are used as: semiconductors, masers, lasers, superconductors, magnetic cooling elements, and heatproof and pliable alloys.