PTL:Samarium

From ChemEd Collaborative

**Samarium**
Symbol:	Sm
Atomic Number:	62
Atomic Weight:	150.36(3)
Electron Configuration:	[Xe] 4f⁶ 6s²
Atomic Radius:	180.2pm
Melting Point:	1074°C
Boiling Point:	1794°C
Heat of Fusion:	8.63kJ/mol
Heat of Vaporization:	166.4kJ/mol
Specific Heat Capacity:	0.20J/gK

Samarium metal is in the lanthanide series of elements, which stretches from lanthanum (La) through lutetium (Lu). Like many of these elements, it has common oxidation numbers of +2 and +3.

1 Discovered
2 Characteristics
3 Uses
4 Emission Spectra

Discovered

Like cesium, rubidium, thallium, and indium, Sm was discovered spectroscopically. It was found by Lecoq de Boisbaudran in 1879 in the mineral samarskite [(Y,Fe³⁺,U)(Nb,Ta)₅O₄], which had been named in honor of a Russian mine official. Its commercial sources today, like most of the other lanthanides, are the minerals monazite [(Ce,Y,La,Nd,Th)PO₄] and bastnasite (Ln₂F₃(CO₃)₂ Ln symbolizes any of the lanthanides but chiefly Cerium).

Minerals Containing Samarium
Samarskite	Monazite	Bastnasite

Characteristics

The metal has a bright silvery luster. However, it does oxidize in air, particularly above 150°C, to give samarium(III) oxide, Sm₂O₃.

Uses

Samarium is used to make magnets such as the ones found in the headphones and tape player above

An alloy with cobalt, SmCo₅, has been used to make [permanent magnets] with the highest resistance to demagnetization of any known material. Such magnets are used in headphones and tape drives.

Samarium can be used as a neutron absorber in nuclear reactors, and samarium oxide is a component of infrared absorbing glass.

Samarium is also used in carbon arc lighting by the motion picture industry.