Lanthanum is a chemical element with the symbol La and 57 is the atomic number of it . It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air and is soft enough to be cut with a knife. It is also sometimes considered the first element of the 6th-period transition metals, which would put it in group 3, although lutetium is sometimes placed in this position instead. It is traditionally counted among the rare earth elements.
The name lanthanum, from the Ancient Greek word lanthanein, meaning “to lie hidden”. Although it is classified as a rare earth element, lanthanum is the 28th most abundant element in the Earth’s crust, almost three times as abundant as lead.
It is usually occurs together with cerium and the other rare earth elements. It was first found by the Swedish chemist Carl Gustav Mosander in 1839 as an impurity in cerium nitrate.
La compounds have numerous applications as catalysts, additives in glass, carbon arc lamps for studio lights and projectors, ignition elements in lighters and torches, electron cathodes and other things. Lanthanum carbonate is used as a phosphate binder in cases of renal failure.
- t is found abundantly in the environment.
- It appears like a white- silvery metal.
- This metal is soft in nature and also active and ductile.
- On reaction with water, this metal oxidizes forming its hydroxide.
- The salts of La are insoluble in water.
- About 12.000 tonnes of La is produced worldwide every year.
- It is often considered to be a group 3 element, along with its lighter congeners scandium and yttrium and its heavier congener, the radioactive actinium, although this classification is sometimes disputed. Similarly to scandium, yttrium, and actinium,
- It is the most reactive among them, tarnishing slowly in air and burning readily to form lanthanum(III) oxide, La2O3, which is almost as basic as calcium oxide.
- A centimeter-sized sample of lanthanum will corrode completely in a year as its oxide spalls off like iron rust, instead of forming a protective oxide coating like aluminium and lanthanum’s lighter congeners scandium and yttrium.
- Lanthanum reacts with the halogens at room temperature to form the trihalides, and upon warming will form binary compounds with the nonmetals nitrogen, carbon, sulfur, phosphorus, boron, selenium, silicon and arsenic.
- Lanthanum reacts slowly with water to form lanthanum(III) hydroxide, In dilute sulfuric acid, lanthanum readily forms the aquated tripositive ion [La(H2O)9]3+: this is colorless in aqueous solution since La3+ has no f electrons.
- Lanthanum is the strongest and hardest base among the lanthanides and group 3 elements, which is again expected from its being the largest of them.