Difference between revisions of "Samarium"
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|above= | |above= | ||
| − | |below= | + | |below=Pu |
| − | |left= | + | |left=Promethium |
| − | |right= | + | |right=[[Europium]] |
| − | |number= | + | |number=62 |
| − | |atomic mass= | + | |atomic mass=150.36(2) |
|atomic mass 2= | |atomic mass 2= | ||
|atomic mass ref= | |atomic mass ref= | ||
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|group ref= | |group ref= | ||
|group comment= | |group comment= | ||
| − | |period= | + | |period=6 |
|period ref= | |period ref= | ||
|period comment= | |period comment= | ||
| − | |block= | + | |block=f |
|block ref= | |block ref= | ||
|block comment= | |block comment= | ||
| − | |electron configuration= | + | |electron configuration=[Xe] 4f<sup>6</sup> 6s<sup>2</sup> |
|electron configuration ref= | |electron configuration ref= | ||
|electron configuration comment= | |electron configuration comment= | ||
| − | |electrons per shell= | + | |electrons per shell=2, 8, 18, 24, 8, 2 |
|electrons per shell ref= | |electrons per shell ref= | ||
|electrons per shell comment= | |electrons per shell comment= | ||
<!-- Physical properties --> | <!-- Physical properties --> | ||
|physical properties comment= | |physical properties comment= | ||
| − | |color= | + | |color=Silvery-gray |
| − | |phase= | + | |phase=Solid |
|phase ref= | |phase ref= | ||
|phase comment= | |phase comment= | ||
| − | |melting point K= | + | |melting point K=1345 |
| − | |melting point C= | + | |melting point C=1072 |
| − | |melting point F= | + | |melting point F=1962 |
|melting point ref= | |melting point ref= | ||
|melting point comment= | |melting point comment= | ||
| − | |boiling point K= | + | |boiling point K=2173 |
| − | |boiling point C= | + | |boiling point C=1900 |
| − | |boiling point F= | + | |boiling point F=3452 |
|boiling point ref= | |boiling point ref= | ||
|boiling point comment= | |boiling point comment= | ||
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|density gplstp ref= | |density gplstp ref= | ||
|density gplstp comment= | |density gplstp comment= | ||
| − | |density gpcm3nrt= | + | |density gpcm3nrt=7.52 |
|density gpcm3nrt ref= | |density gpcm3nrt ref= | ||
|density gpcm3nrt comment= | |density gpcm3nrt comment= | ||
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|density gpcm3nrt 3 ref= | |density gpcm3nrt 3 ref= | ||
|density gpcm3nrt 3 comment= | |density gpcm3nrt 3 comment= | ||
| − | |density gpcm3mp= | + | |density gpcm3mp=7.16 |
|density gpcm3mp ref= | |density gpcm3mp ref= | ||
|density gpcm3mp comment= | |density gpcm3mp comment= | ||
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|critical point ref= | |critical point ref= | ||
|critical point comment= | |critical point comment= | ||
| − | |heat fusion= | + | |heat fusion=8.62 |
|heat fusion ref= | |heat fusion ref= | ||
|heat fusion comment= | |heat fusion comment= | ||
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|heat fusion 2 ref= | |heat fusion 2 ref= | ||
|heat fusion 2 comment= | |heat fusion 2 comment= | ||
| − | |heat vaporization= | + | |heat vaporization=192 |
|heat vaporization ref= | |heat vaporization ref= | ||
|heat vaporization comment= | |heat vaporization comment= | ||
| − | |heat capacity= | + | |heat capacity=29.54 |
|heat capacity ref= | |heat capacity ref= | ||
|heat capacity comment= | |heat capacity comment= | ||
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|heat capacity 2 ref= | |heat capacity 2 ref= | ||
|heat capacity 2 comment= | |heat capacity 2 comment= | ||
| − | |vapor pressure 1= | + | |vapor pressure 1=1001 |
| − | |vapor pressure 10= | + | |vapor pressure 10=1106 |
| − | |vapor pressure 100= | + | |vapor pressure 100=1240 |
| − | |vapor pressure 1 k= | + | |vapor pressure 1 k=(1421) |
| − | |vapor pressure 10 k= | + | |vapor pressure 10 k=(1675) |
| − | |vapor pressure 100 k= | + | |vapor pressure 100 k=(2061) |
|vapor pressure ref= | |vapor pressure ref= | ||
|vapor pressure comment= | |vapor pressure comment= | ||
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<!-- Atomic properties --> | <!-- Atomic properties --> | ||
|atomic properties comment= | |atomic properties comment= | ||
| − | |oxidation states= | + | |oxidation states=4, '''3''', 2, 1 |
|oxidation states ref= | |oxidation states ref= | ||
| − | |oxidation states comment= | + | |oxidation states comment=(a mildly basic oxide) |
| − | |electronegativity= | + | |electronegativity=1.17 |
|electronegativity ref= | |electronegativity ref= | ||
|electronegativity comment= | |electronegativity comment= | ||
| − | |ionization energy 1= | + | |ionization energy 1=544.5 |
|ionization energy 1 ref= | |ionization energy 1 ref= | ||
|ionization energy 1 comment= | |ionization energy 1 comment= | ||
| − | |ionization energy 2= | + | |ionization energy 2=1070 |
|ionization energy 2 ref= | |ionization energy 2 ref= | ||
|ionization energy 2 comment= | |ionization energy 2 comment= | ||
| − | |ionization energy 3= | + | |ionization energy 3=2260 |
|ionization energy 3 ref= | |ionization energy 3 ref= | ||
|ionization energy 3 comment= | |ionization energy 3 comment= | ||
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|ionization energy ref= | |ionization energy ref= | ||
|ionization energy comment= | |ionization energy comment= | ||
| − | |atomic radius= | + | |atomic radius=180 |
|atomic radius ref= | |atomic radius ref= | ||
|atomic radius comment= | |atomic radius comment= | ||
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|atomic radius calculated ref= | |atomic radius calculated ref= | ||
|atomic radius calculated comment= | |atomic radius calculated comment= | ||
| − | |covalent radius= | + | |covalent radius=198±8 |
|covalent radius ref= | |covalent radius ref= | ||
|covalent radius comment= | |covalent radius comment= | ||
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|crystal structure prefix= | |crystal structure prefix= | ||
|crystal structure ref= | |crystal structure ref= | ||
| − | |crystal structure comment= | + | |crystal structure comment=Rhombohedral |
|crystal structure 2= | |crystal structure 2= | ||
|crystal structure 2 prefix= | |crystal structure 2 prefix= | ||
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|speed of sound ref= | |speed of sound ref= | ||
|speed of sound comment= | |speed of sound comment= | ||
| − | |speed of sound rod at 20= | + | |speed of sound rod at 20=2130 |
|speed of sound rod at 20 ref= | |speed of sound rod at 20 ref= | ||
|speed of sound rod at 20 comment= | |speed of sound rod at 20 comment= | ||
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|speed of sound rod at r.t. ref= | |speed of sound rod at r.t. ref= | ||
|speed of sound rod at r.t. comment= | |speed of sound rod at r.t. comment= | ||
| − | |thermal expansion= | + | |thermal expansion=12.7 |
|thermal expansion ref= | |thermal expansion ref= | ||
| − | |thermal expansion comment= | + | |thermal expansion comment=(α, poly) |
|thermal expansion at 25= | |thermal expansion at 25= | ||
|thermal expansion at 25 ref= | |thermal expansion at 25 ref= | ||
|thermal expansion at 25 comment= | |thermal expansion at 25 comment= | ||
| − | |thermal conductivity= | + | |thermal conductivity=13.3 |
|thermal conductivity ref= | |thermal conductivity ref= | ||
|thermal conductivity comment= | |thermal conductivity comment= | ||
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|thermal diffusivity ref= | |thermal diffusivity ref= | ||
|thermal diffusivity comment= | |thermal diffusivity comment= | ||
| − | |electrical resistivity= | + | |electrical resistivity=9.4·10<sup>-7</sup> |
|electrical resistivity unit prefix= | |electrical resistivity unit prefix= | ||
|electrical resistivity ref= | |electrical resistivity ref= | ||
| − | |electrical resistivity comment= | + | |electrical resistivity comment=(α, poly) |
|electrical resistivity at 0= | |electrical resistivity at 0= | ||
|electrical resistivity at 0 ref= | |electrical resistivity at 0 ref= | ||
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|Curie point ref= | |Curie point ref= | ||
|Curie point comment= | |Curie point comment= | ||
| − | |magnetic ordering= | + | |magnetic ordering=Paramagnetic |
|magnetic ordering ref= | |magnetic ordering ref= | ||
|magnetic ordering comment= | |magnetic ordering comment= | ||
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|tensile strength ref= | |tensile strength ref= | ||
|tensile strength comment= | |tensile strength comment= | ||
| − | |Young's modulus= | + | |Young's modulus=49.7 |
|Young's modulus ref= | |Young's modulus ref= | ||
| − | |Young's modulus comment= | + | |Young's modulus comment=(α form) |
| − | |Shear modulus= | + | |Shear modulus=19.5 |
|Shear modulus ref= | |Shear modulus ref= | ||
| − | |Shear modulus comment= | + | |Shear modulus comment=(α form) |
| − | |Bulk modulus= | + | |Bulk modulus=37.8 |
|Bulk modulus ref= | |Bulk modulus ref= | ||
| − | |Bulk modulus comment= | + | |Bulk modulus comment=(α form) |
| − | |Poisson ratio= | + | |Poisson ratio=0.274 |
|Poisson ratio ref= | |Poisson ratio ref= | ||
| − | |Poisson ratio comment= | + | |Poisson ratio comment=(α form) |
|Mohs hardness= | |Mohs hardness= | ||
|Mohs hardness ref= | |Mohs hardness ref= | ||
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|Mohs hardness 2 ref= | |Mohs hardness 2 ref= | ||
|Mohs hardness 2 comment= | |Mohs hardness 2 comment= | ||
| − | |Vickers hardness= | + | |Vickers hardness=410–440 |
|Vickers hardness ref= | |Vickers hardness ref= | ||
|Vickers hardness comment= | |Vickers hardness comment= | ||
| − | |Brinell hardness= | + | |Brinell hardness=440–600 |
|Brinell hardness ref= | |Brinell hardness ref= | ||
|Brinell hardness comment= | |Brinell hardness comment= | ||
| − | |CAS number= | + | |CAS number=7440-19-9 |
|CAS number ref= | |CAS number ref= | ||
|CAS number comment= | |CAS number comment= | ||
<!-- History --> | <!-- History --> | ||
| − | |naming= | + | |naming=After the mineral samarskite (itself named after Vassili Samarsky-Bykhovets) |
|predicted by= | |predicted by= | ||
|prediction date ref= | |prediction date ref= | ||
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|first isolation date ref= | |first isolation date ref= | ||
|first isolation date= | |first isolation date= | ||
| − | |discovery and first isolation by= | + | |discovery and first isolation by=Lecoq de Boisbaudran (1879) |
|named by= | |named by= | ||
|named date ref= | |named date ref= | ||
Revision as of 22:22, 21 October 2017
 Samarium metal | |||||
| General properties | |||||
|---|---|---|---|---|---|
| Name, symbol | Samarium, Sm | ||||
| Appearance | Silvery gray | ||||
| Samarium in the periodic table | |||||
| |||||
| Atomic number | 62 | ||||
| Standard atomic weight (Ar) | 150.36(2) | ||||
| Group, block | , f-block | ||||
| Period | period 6 | ||||
| Electron configuration | [Xe] 4f6 6s2 | ||||
per shell | 2, 8, 18, 24, 8, 2 | ||||
| Physical properties | |||||
| Silvery-gray | |||||
| Phase | Solid | ||||
| Melting point | 1345 K (1072 °C, 1962 °F) | ||||
| Boiling point | 2173 K (1900 °C, 3452 °F) | ||||
| Density near r.t. | 7.52 g/cm3 | ||||
| when liquid, at | 7.16 g/cm3 | ||||
| Heat of fusion | 8.62 kJ/mol | ||||
| Heat of | 192 kJ/mol | ||||
| Molar heat capacity | 29.54 J/(mol·K) | ||||
| pressure | |||||
| Atomic properties | |||||
| Oxidation states | 4, 3, 2, 1 (a mildly basic oxide) | ||||
| Electronegativity | Pauling scale: 1.17 | ||||
| energies |
1st: 544.5 kJ/mol 2nd: 1070 kJ/mol 3rd: 2260 kJ/mol | ||||
| Atomic radius | empirical: 180 pm | ||||
| Covalent radius | 198±8 pm | ||||
| Miscellanea | |||||
| Crystal structure | Rhombohedral | ||||
| Speed of sound thin rod | 2130 m/s (at 20 °C) | ||||
| Thermal expansion | 12.7 µm/(m·K) (α, poly) | ||||
| Thermal conductivity | 13.3 W/(m·K) | ||||
| Electrical resistivity | 9.4·10-7 Ω·m (α, poly) | ||||
| Magnetic ordering | Paramagnetic | ||||
| Young's modulus | 49.7 GPa (α form) | ||||
| Shear modulus | 19.5 GPa (α form) | ||||
| Bulk modulus | 37.8 GPa (α form) | ||||
| Poisson ratio | 0.274 (α form) | ||||
| Vickers hardness | 410–440 MPa | ||||
| Brinell hardness | 440–600 MPa | ||||
| CAS Registry Number | 7440-19-9 | ||||
| History | |||||
| Naming | After the mineral samarskite (itself named after Vassili Samarsky-Bykhovets) | ||||
| Discovery and first isolation | Lecoq de Boisbaudran (1879) | ||||
Samarium is a lanthanide with the symbol Sm and atomic number 62. It is a grayish-silvery metal, with similar reactivity to magnesium. Its chemical behavior is similar to most other rare earth metal, but it is notable for the presence of a blood-red samarium (II) ion in reducing conditions.
Contents
Properties
Physical properties
Samarium is a grayish metal that is about as dense as iron or manganese. Freshly cut pieces are very shiny and lustrous, while older ones are generally darker from a thin oxide layer. It is very slightly paramagnetic - more so than vanadium, but less than europium, and can be very easily demonstrated by placing a piece on a styrofoam block on water and pulling it with a neodymium magnet.
Chemical properties
As a lanthanide, samarium is quite reactive, but its corrosion resistance is between that of the light and heavy rare earth metals. Exposure to air will eventually turn it to a white powdery oxide, but it is nowhere near as reactive as europium or lanthanum. It burns in air to from yellowish samarium(III) oxide in a bright red flame. It reacts only sluggishly with iodine to form samarium(III) iodide.
Samarium is notable for the existence of a dipositive ion, samarium(II), which is a strong reducing agent, as the tripositive ion is more stable. Its most common form, samarium(II) iodide, will reduce water and acids to hydrogen, and is an effective one-electron reductor for organic synthesis (the Barbier reaction is its most notable use, and it's well known for catalyzing the pinacol coupling). Its dramatic color change from nearly black to pale yellow in THF makes it an excellent redox indicator as well. The dipositive ion, which forms a blood-red to mauve coloration, has occasionally been observed when samarium metal is placed in hydrochloric acid, though it appears to be quickly oxidized upon production. A standard laboratory prep for the compound is addition of the metal to a solution of 1,2-diiodoethane in tetrahydrofuran.
Availability and preparation
Samarium is more common than iodine on Earth, but it is hard to find and expensive. It is, however, one of the cheapest lanthanides, along with gadolinium. One source for samarium, as well as other rare earth metals, is Metallium. It is sold in 5 and 40 gram sizes, as well as rods, ampoules, and coins. Samarium metal is sold in even larger amounts on eBay, but Metallium also takes custom orders of turnings, large cast ingots, and powders. Samarium(III) oxide is relatively cheap among rare-earth compounds, and can be reduced to samarium metal with lanthanum powder in a thermite-like reaction. The most common way to extract elemental samarium, however, is the electrolysis of molten anhydrous samarium(III) chloride.
Projects
- Red pyrotechnic mixtures
- Reductions with samarium(II) iodide
- Dissolving samarium in liquid ammonia to produce solvated electrons
The mysteries of samarium(II)
Work has been done on the stability of the samarium(II) ion in aqueous solution, but research is incomplete. It is also unknown how to coax samarium to react with iodine, as the reaction is very sluggish.
Safety
Storage
Samarium metal tends to corrode, so sealing it in an airtight container is recommended. Mineral oil also helps with preservation of the metal. Samarium does not corrode as fast as europium, calcium, or sodium, so taking it out in air for a few minutes at a time will not affect the sample.
Toxicity
Samarium compounds have not been investigated for their toxicity, and should be treated as mildly toxic. Salts of samarium, especially the halides, tend to hydrolyze at elevated temperatures and may emit noxious or strongly acidic vapors.
Flammability
Samarium as small pieces will ignite in the presence of an open flame, and samarium dust and powder may ignite spontaneously in air. Samarium and europium fires can be identified due to their bright red flames. Class D fire extingushers should be at hand. Water may aggravate burning samarium and should never be used.
