|Boiling Point: 2067oK, 1794oC, 3261oF
Melting Point: 1345oK, 1072oC, 1962oF
Electrons Energy Level: 2, 8, 18, 24, 8, 2
Isotopes: 38 + 5 Stable + 5 meta states
Heat of Vaporization: 165 kJ/mol
Heat of Fusion: 8.62 kJ/mol
Density: 7.52g/cm3 @ 300oK
Specific Heat: 0.2 J/goK
Atomic Radius: 2.59Å
Ionic Radius: 0.964Å
Electronegativity: 1.17 (Pauling), 1.07 (Allrod Rochow)
Vapor Pressure: 563 Pa @ 1072°C
1s2 2s2p6 3s2p6d10 4s2p6d10f6 5s2p6 6s2
Named for the mineral samarskite from which it is extracted. Samarium was first discovered spectroscopically, in a material known as dydimia, in 1853 by Swiss chemist Jean Charles Galissard de Marignac by its sharp absorption lines in didymium and isolated and identified in Paris in 1879 by French chemist Paul Emile Lecoq de Boisbaudran from the mineral samarskite (Y,Ce,U,Fe)3(Nb,Ta,Ti)5O16.
The samarskite mineral was named after Vasili Samarsky-Bykhovets, the Chief of Staff (Colonel) of the Russian Corps of Mining Engineers in 18451861. The name of the element is derived from the name of the mineral, and thus traces back to the name Samarsky-Bykhovets. In this sense samarium was the first chemical element to be named after a living person.
The pure metal has a silver lustre and tarnishes slowly at room conditions. It is readily magnetized and holds its magnetism extremely well. Rare earth magnets (samarium-cobalt, for example) exploit this property.
Although it is present in samarskite, commercial production of samarium is from monazite sand, (Ce, La, Th, Nd, Y)PO4, which can contain as much as 2.8% Sm by weight.
Samarium is a rare earth metal, with a bright silver luster, that is reasonably stable in air; it ignites in air at 150°C. Even with long-term storage under mineral oil, samarium is gradually oxidized, with a grayish-yellow powder of the oxide-hydroxide being formed. Three crystal modifications of the metal also exist, with transformations at 734 and 922°C.
The sulfide has excellent high-temperature stability and good thermoelectric efficiencies up to 1100oC.
Samarium is never found free in nature, but, like other rare earth elements, is contained in many minerals, including monazite, bastnasite and samarskite; monazite (in which it occurs up to an extent of 2.8%) and bastnasite are also used as commercial sources. Misch metal containing about 1% of samarium has long been used, but it was not until recent years that relatively pure samarium has been isolated through ion exchange processes, solvent extraction techniques, and electrochemical deposition. The metal is often prepared by electrolysis of a molten mixture of samarium (III) chloride with sodium chloride or calcium chloride. Samarium can also be obtained by reducing its oxide with lanthanum.
Samarium is one of the rare earth elements used to make carbon arc lights which are used in the motion picture industry for studio lighting and projector lights. Samarium also makes up about 1% of Misch metal, a material that is used to make flints for lighters.
Ion-exchange and solvent extraction techniques have recently simplified separation of the rare earths from one another; more recently, electrochemical deposition, using an electrolytic solution of lithium citrate and a mercury electrode, is said to be a simple, fast, and highly specific way to separate the rare earths. Samarium metal can be produced by reducing the oxide with lanthanum.
Samarium forms a compound with cobalt (SmCo5) which is a powerful permanent magnet with the highest resistance to demagnetization of any material known. Samarium oxide (Sm2O3) is added to glass to absorb infrared radiation and acts as a catalyst for the dehydration and dehydrogenation of ethanol (C2H6O).
Naturally occurring samarium is composed of 5 stable isotopes, 144Sm, 150Sm, 152Sm and 154Sm, and 3 radioisotopes, 147Sm, 148Sm and 149Sm, with 152Sm being the most abundant (26.75% natural abundance. 38 radioisotopes have been characterized, with the most stable being 148Sm with a half-life of 7x1015 years, 149Sm with a half-life of more than 2x1015 years, and 147Sm with a half-life of 1.06x1011 years. All of the remaining radioactive isotopes have half-lifes that are less than 1.04x108 years, and the majority of these have half lifes that are less than 48 seconds. This element also has 5 meta states with the most stable being 141mSm (t½ 22.6 minutes), 143m1Sm (t½ 66 seconds) and 139mSm (t½ 10.7 seconds).
The primary decay mode before the most abundant stable isotope, 152Sm, is electron capture, and the primary mode after is beta minus decay. The primary decay products before 152Sm are element Pm (promethium) isotopes, and the primary products after are element Eu (europium) isotopes.
|146Sm||145.913041||1.03 x 108 years|
|147Sm||146.9148979||106.0 x 1012 years|
|148Sm||147.9148227||7 x 1015 years|
|As with the other lanthanides, samarium compounds are of low to moderate toxity, although their toxicity has not been investigated in detail. It ignites in air at 150°C.|
Atomic Radius (Å): 2.59Å
Electrochemical Equivalents: 1.87g/amp-hr
Atomic Mass Average: 150.36
Fusion Heat (kJ/mol): 8.9