Difference between revisions of "Europium" - New World Encyclopedia
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{{Elementbox_vickershardness_mpa | 167 }} | {{Elementbox_vickershardness_mpa | 167 }} | ||
{{Elementbox_cas_number | 7440-53-1 }} | {{Elementbox_cas_number | 7440-53-1 }} | ||
− | {{Elementbox_isotopes_begin | color1=#ffbfff | color2=black }} | + | {{Elementbox_isotopes_begin | isotopesof=europium | color1=#ffbfff | color2=black }} |
{{Elementbox_isotopes_decay | mn=150 | sym=Eu | {{Elementbox_isotopes_decay | mn=150 | sym=Eu | ||
| na=[[synthetic radioisotope|syn]] | hl=[[1 E s|36.9 y]] | | na=[[synthetic radioisotope|syn]] | hl=[[1 E s|36.9 y]] | ||
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{{Elementbox_footer | color1=#ffbfff | color2=black }} | {{Elementbox_footer | color1=#ffbfff | color2=black }} | ||
− | '''Europium''' ([[ | + | '''Europium''' ([chemical symbol '''Eu''', [[atomic number]] 63) is the most reactive of the [[rare earth element]]s. It was named after the continent [[Europe]]. |
+ | |||
+ | == Occurrence == | ||
+ | |||
+ | Europium is never found in nature as a free element; however, there are many minerals containing europium, with the most important sources being [[bastnäsite]] and [[monazite]]. Europium has also been identified in the spectra of the sun and certain stars. | ||
+ | |||
+ | == History == | ||
+ | |||
+ | Europium was first found by [[Paul Émile Lecoq de Boisbaudran]] in [[1890]], who obtained basic fraction from [[samarium]]-[[gadolinium]] concentrates which had spectral lines not accounted for by [[samarium]] or [[gadolinium]]; however, the discovery of europium is generally credited to [[France|French]] [[chemist]] [[Eugène-Antole Demarçay]], who suspected samples of the recently discovered element [[samarium]] were contaminated with an unknown element in [[1896]] and who was able to isolate europium in [[1901]]. | ||
== Notable characteristics == | == Notable characteristics == | ||
− | |||
− | + | Europium instantly oxidizes in air, and resembles [[calcium]] in its reaction with water; deliveries of the metal element in solid form even under mineral oil are rarely shiny. Europium ignites in air at about 150 °C to 180 °C. It is about as hard as lead and quite ductile. | |
− | |||
− | + | === Isotopes === | |
− | + | Naturally occurring europium is composed of 2 stable [[isotope]]s, 151-Eu and 153-Eu, with 153-Eu being the most abundant (52.2% [[natural abundance]]). 35 [[radioisotope]]s have been characterized, with the most stable being 150-Eu with a [[half-life]] of 36.9 years, 152-Eu with a half-life of 13.516 years, and 154-Eu with a half-life of 8.593 years. All of the remaining [[radioactive]] isotopes have half-lifes that are less than 4.7612 years, and the majority of these have half lifes that are less than 12.2 seconds. This element also has 8 [[meta state]]s, with the most stable being 150m-Eu (t<sub>½</sub> 12.8 hours), 152m1-Eu (t<sub>½</sub> 9.3116 hours) and 152m2-Eu (t<sub>½</sub> 96 minutes). | |
− | |||
− | + | The primary [[decay mode]] before the most abundant stable isotope, 153-Eu, is [[electron capture]], and the primary mode after is [[beta minus decay]]. The primary [[decay product]]s before 153-Eu are element Sm ([[samarium]]) isotopes and the primary products after are element Gd ([[gadolinium]]) isotopes. | |
− | |||
== Compounds == | == Compounds == | ||
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** [[europium(III) nitride|EuN]] | ** [[europium(III) nitride|EuN]] | ||
Europium(II) compounds tend to predominate, in contrast to most [[lanthanide]]s (which generally form compounds with an oxidation state of +3). Europium(II) chemistry is very similar to [[barium]](II) chemistry, as they have similar [[ionic radius|ionic radii]]. | Europium(II) compounds tend to predominate, in contrast to most [[lanthanide]]s (which generally form compounds with an oxidation state of +3). Europium(II) chemistry is very similar to [[barium]](II) chemistry, as they have similar [[ionic radius|ionic radii]]. | ||
+ | |||
''See also [[:Category:Europium compounds|europium compounds]].'' | ''See also [[:Category:Europium compounds|europium compounds]].'' | ||
− | == | + | == Applications == |
− | + | ||
+ | There are few commercial applications for europium metal, although it has been used to dope some types of [[glass]] to make [[laser]]s, as well as being used for screening for [[Down syndrome]] and some other genetic diseases. Due to its ability to absorb neutrons, it is also being studied for use in nuclear reactors. Europium oxide (Eu<sub>2</sub>O<sub>3</sub>) is widely used as a red [[phosphor]] in [[Cathode ray tube|television sets]] and [[fluorescent lamps]], and as an activator for [[yttrium]]-based phosphors. It is also being used as an agent for the manufacture of fluorescent glass. <!--A salt of Europium is a component of the newer phosphorescent powders and paints, some of which will glow for days after a few minutes of exposure to light. PLEASE SEE TALK —> Europium fluorescence is used to interogate biomolecular interactions in drug-discovery screens. It is also used in the anti-counterfeiting phosphors in [[Euro]] banknotes. <ref> Europium and the Euro [http://www.smarterscience.com/eurosandeuropium.html]</ref> | ||
− | + | Europium is commonly included in trace element studies in [[geochemistry]] and [[petrology]] to understand the processes that form [[igneous rocks]] (rocks that cooled from [[magma]] or [[lava]]). The nature of the [[europium anomaly]] found is used to help reconstruct the relationships within a suite of igneous rocks. | |
== Precautions == | == Precautions == | ||
The toxicity of europium compounds has not been fully investigated, but there are no clear indications that europium is highly toxic compared to other heavy metals. The metal dust presents a fire and explosion hazard. Europium has no known biological role. | The toxicity of europium compounds has not been fully investigated, but there are no clear indications that europium is highly toxic compared to other heavy metals. The metal dust presents a fire and explosion hazard. Europium has no known biological role. | ||
+ | |||
+ | == See also == | ||
+ | |||
+ | * [[Inner transition metal]] | ||
+ | * [[Lanthanum]] | ||
+ | |||
+ | == Footnotes == | ||
+ | <references/> | ||
== References == | == References == | ||
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== External links == | == External links == | ||
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* [http://www.webelements.com/webelements/elements/text/Eu/index.html WebElements.com – Europium] | * [http://www.webelements.com/webelements/elements/text/Eu/index.html WebElements.com – Europium] | ||
* [http://education.jlab.org/itselemental/ele063.html It's Elemental – Europium] | * [http://education.jlab.org/itselemental/ele063.html It's Elemental – Europium] | ||
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[[Category:Chemical elements]] | [[Category:Chemical elements]] | ||
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Revision as of 21:59, 6 February 2007
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General | ||||||||||||||||||||||||||||||||||
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Name, Symbol, Number | europium, Eu, 63 | |||||||||||||||||||||||||||||||||
Chemical series | lanthanides | |||||||||||||||||||||||||||||||||
Group, Period, Block | n/a, 6, f | |||||||||||||||||||||||||||||||||
Appearance | silvery white | |||||||||||||||||||||||||||||||||
Atomic mass | 151.964(1) g/mol | |||||||||||||||||||||||||||||||||
Electron configuration | [Xe] 4f7 6s2 | |||||||||||||||||||||||||||||||||
Electrons per shell | 2, 8, 18, 25, 8, 2 | |||||||||||||||||||||||||||||||||
Physical properties | ||||||||||||||||||||||||||||||||||
Phase | solid | |||||||||||||||||||||||||||||||||
Density (near r.t.) | 5.264 g/cm³ | |||||||||||||||||||||||||||||||||
Liquid density at m.p. | 5.13 g/cm³ | |||||||||||||||||||||||||||||||||
Melting point | 1099 K (826 °C, 1519 °F) | |||||||||||||||||||||||||||||||||
Boiling point | 1802 K (1529 °C, 2784 °F) | |||||||||||||||||||||||||||||||||
Heat of fusion | 9.21 kJ/mol | |||||||||||||||||||||||||||||||||
Heat of vaporization | 176 kJ/mol | |||||||||||||||||||||||||||||||||
Heat capacity | (25 °C) 27.66 J/(mol·K) | |||||||||||||||||||||||||||||||||
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Atomic properties | ||||||||||||||||||||||||||||||||||
Crystal structure | simple cubic (body centered) | |||||||||||||||||||||||||||||||||
Oxidation states | 3,2 (mildly basic oxide) | |||||||||||||||||||||||||||||||||
Electronegativity | ? 1.2 (Pauling scale) | |||||||||||||||||||||||||||||||||
Ionization energies (more) |
1st: 547.1 kJ/mol | |||||||||||||||||||||||||||||||||
2nd: 1085 kJ/mol | ||||||||||||||||||||||||||||||||||
3rd: 2404 kJ/mol | ||||||||||||||||||||||||||||||||||
Atomic radius | 185 pm | |||||||||||||||||||||||||||||||||
Atomic radius (calc.) | 231 pm | |||||||||||||||||||||||||||||||||
Miscellaneous | ||||||||||||||||||||||||||||||||||
Magnetic ordering | no data | |||||||||||||||||||||||||||||||||
Electrical resistivity | (r.t.) (poly) 0.900 µΩ·m | |||||||||||||||||||||||||||||||||
Thermal conductivity | (300 K) est. 13.9 W/(m·K) | |||||||||||||||||||||||||||||||||
Thermal expansion | (r.t.) (poly) 35.0 µm/(m·K) | |||||||||||||||||||||||||||||||||
Speed of sound (thin rod) | (r.t.) 18.2 m/s | |||||||||||||||||||||||||||||||||
Shear modulus | 7.9 GPa | |||||||||||||||||||||||||||||||||
Bulk modulus | 8.3 GPa | |||||||||||||||||||||||||||||||||
Poisson ratio | 0.152 | |||||||||||||||||||||||||||||||||
Vickers hardness | 167 MPa | |||||||||||||||||||||||||||||||||
CAS registry number | 7440-53-1 | |||||||||||||||||||||||||||||||||
Notable isotopes | ||||||||||||||||||||||||||||||||||
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Europium ([chemical symbol Eu, atomic number 63) is the most reactive of the rare earth elements. It was named after the continent Europe.
Occurrence
Europium is never found in nature as a free element; however, there are many minerals containing europium, with the most important sources being bastnäsite and monazite. Europium has also been identified in the spectra of the sun and certain stars.
History
Europium was first found by Paul Émile Lecoq de Boisbaudran in 1890, who obtained basic fraction from samarium-gadolinium concentrates which had spectral lines not accounted for by samarium or gadolinium; however, the discovery of europium is generally credited to French chemist Eugène-Antole Demarçay, who suspected samples of the recently discovered element samarium were contaminated with an unknown element in 1896 and who was able to isolate europium in 1901.
Notable characteristics
Europium instantly oxidizes in air, and resembles calcium in its reaction with water; deliveries of the metal element in solid form even under mineral oil are rarely shiny. Europium ignites in air at about 150 °C to 180 °C. It is about as hard as lead and quite ductile.
Isotopes
Naturally occurring europium is composed of 2 stable isotopes, 151-Eu and 153-Eu, with 153-Eu being the most abundant (52.2% natural abundance). 35 radioisotopes have been characterized, with the most stable being 150-Eu with a half-life of 36.9 years, 152-Eu with a half-life of 13.516 years, and 154-Eu with a half-life of 8.593 years. All of the remaining radioactive isotopes have half-lifes that are less than 4.7612 years, and the majority of these have half lifes that are less than 12.2 seconds. This element also has 8 meta states, with the most stable being 150m-Eu (t½ 12.8 hours), 152m1-Eu (t½ 9.3116 hours) and 152m2-Eu (t½ 96 minutes).
The primary decay mode before the most abundant stable isotope, 153-Eu, is electron capture, and the primary mode after is beta minus decay. The primary decay products before 153-Eu are element Sm (samarium) isotopes and the primary products after are element Gd (gadolinium) isotopes.
Compounds
Europium compounds include:
- Fluorides
- Chlorides
- Bromides
- Iodides
- Oxides
- Sulfides
- EuS
- Selenides
- EuSe
- Tellurides
- EuTe
- Nitrides
- EuN
Europium(II) compounds tend to predominate, in contrast to most lanthanides (which generally form compounds with an oxidation state of +3). Europium(II) chemistry is very similar to barium(II) chemistry, as they have similar ionic radii.
See also europium compounds.
Applications
There are few commercial applications for europium metal, although it has been used to dope some types of glass to make lasers, as well as being used for screening for Down syndrome and some other genetic diseases. Due to its ability to absorb neutrons, it is also being studied for use in nuclear reactors. Europium oxide (Eu2O3) is widely used as a red phosphor in television sets and fluorescent lamps, and as an activator for yttrium-based phosphors. It is also being used as an agent for the manufacture of fluorescent glass. Europium fluorescence is used to interogate biomolecular interactions in drug-discovery screens. It is also used in the anti-counterfeiting phosphors in Euro banknotes. [1]
Europium is commonly included in trace element studies in geochemistry and petrology to understand the processes that form igneous rocks (rocks that cooled from magma or lava). The nature of the europium anomaly found is used to help reconstruct the relationships within a suite of igneous rocks.
Precautions
The toxicity of europium compounds has not been fully investigated, but there are no clear indications that europium is highly toxic compared to other heavy metals. The metal dust presents a fire and explosion hazard. Europium has no known biological role.
See also
Footnotes
ReferencesISBN links support NWE through referral fees
External links
Credits
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