Einsteinium
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Albert Einstein Einsteinium (pronounced ine-STINE-i-em) is a metallicman-madeelement. On the periodic table, it is represented by the symbol Es and atomic number 99. Einsteinium is the seventh transuranic element, and an actinide. The actinides are the elements found in the last row of the periodic table, having atomic numbers between 89 and 103, and a transuranic element is one that has a higher atomic number than uranium, and isman-made and not found in nature. It was named in honor of Albert Einstein.
Contents
Properties
Though only small amounts have been made, einsteinium has been determined to be silver-colored. According to tracer studies conducted by Los Alamos National Laboratory using the isotope 253Es, this element has chemical properties typical of a heavy trivalent actinideelement. All isotopes of einsteinium are radioactive, and are considered to be potentially toxic.
Production
Einsteinium does not occur naturally in any measurable quantities. The modern process of creating the element starts with the irradiation of 239Pu (plutonium) in a nuclear reactor for several years. The resulting 242Pu isotope (in the form of the compound plutonium (IV) oxide) is mixed with aluminumand formed into pellets. The pellets then undergo extensive and successive nuclear reactions resulting in a mixture of Californiumand einsteinium, which can then be separated.
| Previous Element: Californium Next Element: Fermium |
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| Physical Properties | ||
|---|---|---|
| Color | --- | |
| Phase at Room Temp. | --- | |
| Density (g/cm3) | --- | |
| Hardness (Mohs) | --- | |
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Melting Point (K) |
1133.2 | |
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Boiling Point (K) |
--- | |
| Heat of Fusion (kJ/mol) | --- | |
| Heat of Vaporization (kJ/mol) | --- | |
| Heat of Atomization (kJ/mol) | --- | |
| Thermal Conductivity (J/m sec K) | --- | |
| Electrical Conductivity (1/mohm cm) | --- | |
| Source | Synthetic | |
| Atomic Properties | ||
| Electron Configuration | [Rn]7s25f11 | |
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Number of Isotopes |
20 (0 natural) | |
| Electron Affinity (kJ/mol) | --- | |
| First Ionization Energy (kJ/mol) | 619 | |
| Second Ionization Energy (kJ/mol) | --- | |
| Third Ionization Energy (kJ/mol) | --- | |
| Electronegativity | 1.3 | |
| Polarizability (Å3) | 19.7 | |
| Atomic Weight | 252.1 | |
| Atomic Volume (cm3/mol) | --- | |
| Ionic Radius2- (pm) | --- | |
| Ionic Radius1- (pm) | --- | |
| Atomic Radius (pm) | 186 | |
| Ionic Radius1+ (pm) | --- | |
| Ionic Radius2+ (pm) | --- | |
| Ionic Radius3+ (pm) | --- | |
| Common Oxidation Numbers | +3 | |
| Other Oxid. Numbers | +2 | |
| Abundance | ||
| In Earth's Crust (mg/kg) | --- | |
| In Earth's Ocean (mg/L) | --- | |
| In Human Body (%) | --- | |
| Regulatory / Health | ||
| CAS Number | 7429-92-7 | |
| OSHA Permissible Exposure Limit (PEL) | No limits | |
| OSHA PEL Vacated 1989 | No limits | |
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NIOSH Recommended Exposure Limit (REL) |
No limits | |
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Uses
In addition toitsrolein basic scientific research in which einsteinium is used to produce other elements, such as mendelevium, this man-made element has no known uses. Only a few compounds of einsteinium have ever been discovered, and none of them have any commercial uses or biological roles. In large amounts, the production of einsteinium could pose a radiationthreat.
History
Einsteinium was first identified in December 1952 by Albert Ghiorso along with co-workers at the University of California, Berkeley. He was examining debris from the first hydrogen bomb test of November 1952. He discovered the isotope253Es with a half-life of 20.47 days, which was made by the neutron capture of 15 neutrons with 238U (uranium), which then went through 7 beta decays. These findings were kept secret until 1955 because at the time information about atomic tests was restricted.
Isotopes of einsteinium were produced shortly afterward at the University of California Radiation Laboratory by bombarding 238U with 14N (nitrogen) ions, and later by the intense bombardment of neutrons of 239Pu in the Materials Testing Reactor.
In 1961, enough einsteinium was synthesized to prepare a microscopic amount of 253Es. This sample weighed about 0.01 mg (milligrams) and was measured using a special balance. The material produced was used to produce mendelevium. Further einsteinium has been produced as the Oak Ridge National Laboratory’s High Flux Isotope Reactor in Tennessee by bombarding 239Pu with neutrons. Around 3 mg were created during a program of irradiationfollowed by chemical separation from a starting 1 kg (kilogram) of the plutonium isotope.
Isotopes
Nineteen radioisotopes of einsteinium have been characterized, with the most stable being:
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All of the remaining isotopes are all also radioactiveand have half-lives that are less than 40 hours, with the majority of these having half-lives that are less than 30 minutes. This element also has four isotopes that decay by more than one path, and therefore have more than one half-life.
Known Compounds
The following is a list of all known compounds of einsteinium:
- EsBr3 Einsteinium (III) Bromide
- EsCl2 Einsteinium (II) Chloride
- EsCl3 Einsteinium (III) Chloride
- EsF3 Einsteinium (III) Fluoride
- EsI2 Einsteinium (II) Iodide
- EsI3 Einsteinium (III) Iodide
- Es2O3 Einsteinium (III) Oxide
Further Reading
- Einsteinium – National Research Council Canada. Retrieved 9/22/2009
- Einsteinium– Los Alamos National Laboratory. Retrieved 10/7/2009
- It’s Elemental – The Element Einsteinium. Retrieved 10/7/2009
- Albert Ghiorso. Einsteinium and Fermium. Chemical and Engineering News. 2003. Retrieved 9/28/2009
- National Nuclear Data Center. NuDat 2.5. 2009. Retrieved 9/28/200
- David L. Heiserman. Exploring Chemical Elements and their Compounds: A guided tour of the Periodic Table. TAB Books, USA. 1992. Pp 349-350
- Albert Stwertka. A Guide to the Elements. Second Edition. Oxford University Press, New York, New York. 2002. Pp 214
- The New Encyclopedia Britannica. 15th Edition. 2007. Volume 4 pp 403
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