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Berkelium is a transuranic radioactive chemical element with the symbol Bk and atomic number 97. It is a member of the actinide and transuranium element series. It is named after the city of Berkeley, California, the location of the Lawrence Berkeley National Laboratory where it was discovered in December 1949. Berkelium was the fifth transuranium element discovered after neptunium, plutonium, curium and americium.
Curium is a transuranic, radioactive chemical element with the symbol Cm and atomic number 96. This actinide element was named after eminent scientists Marie and Pierre Curie, both known for their research on radioactivity. Curium was first intentionally made by the team of Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso in 1944, using the cyclotron at Berkeley. They bombarded the newly discovered element plutonium with alpha particles. This was then sent to the Metallurgical Laboratory at University of Chicago where a tiny sample of curium was eventually separated and identified. The discovery was kept secret until after the end of World War II. The news was released to the public in November 1947. Most curium is produced by bombarding uranium or plutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains ~20 grams of curium.
In crystallography, the cubiccrystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals.
Curium(III) oxide is a compound composed of curium and oxygen with the chemical formula Cm2O3. It is a crystalline solid with a unit cell that contains two curium atoms and three oxygen atoms. The simplest synthesis equation involves the reaction of curium(III) metal with O2−: 2 Cm3+ + 3 O2− ---> Cm2O3. Curium trioxide can exist as five polymorphic forms. Two of the forms exist at extremely high temperatures, making it difficult for experimental studies to be done on the formation of their structures. The three other possible forms which curium sesquioxide can take are the body-centered cubic form, the monoclinic form, and the hexagonal form. Curium(III) oxide is either white or light tan in color and, while insoluble in water, is soluble in inorganic and mineral acids. Its synthesis was first recognized in 1955.
Few compounds of californium have been made and studied. The only californium ion that is stable in aqueous solutions is the californium(III) cation. The other two oxidation states are IV (strong oxidizing agents) and II (strong reducing agents). The element forms a water-soluble chloride, nitrate, perchlorate, and sulfate and is precipitated as a fluoride, oxalate or hydroxide. If problems of availability of the element could be overcome, then CfBr2 and CfI2 would likely be stable.
Berkelium forms a number of chemical compounds, where it normally exists in an oxidation state of +3 or +4, and behaves similarly to its lanthanide analogue, terbium. Like all actinides, berkelium easily dissolves in various aqueous inorganic acids, liberating gaseous hydrogen and converting into the trivalent oxidation state. This trivalent state is the most stable, especially in aqueous solutions, but tetravalent berkelium compounds are also known. The existence of divalent berkelium salts is uncertain and has only been reported in mixed lanthanum chloride-strontium chloride melts. Aqueous solutions of Bk3+ ions are green in most acids. The color of the Bk4+ ions is yellow in hydrochloric acid and orange-yellow in sulfuric acid. Berkelium does not react rapidly with oxygen at room temperature, possibly due to the formation of a protective oxide surface layer; however, it reacts with molten metals, hydrogen, halogens, chalcogens and pnictogens to form various binary compounds. Berkelium can also form several organometallic compounds.
Berkelium(IV) oxide, also known as berkelium dioxide, is a chemical compound with the formula BkO2. This compound slowly decays to californium(IV) oxide. It can be converted to berkelium(III) oxide by hydrogen reduction at 600 °C.
Curium compounds are compounds containing the element curium (Cm). Curium usually forms compounds in the +3 oxidation state, although compounds with curium in the +4, +5 and +6 oxidation states are also known.
Neodymium(III) hydride is an inorganic compound composed of neodymium and hydrogen with a chemical formula NdH3. In this compound, the neodymium atom is in the +3 oxidation state and the hydrogen atoms are -1. It is highly reactive.
Einsteinium compounds are compounds that contain the element einsteinium (Es). These compounds largely have einsteinium in the +3 oxidation state, or in some cases in the +2 and +4 oxidation states. Although einsteinium is relatively stable, with half-lives ranging from 20 days upwards, these compounds have not been studied in great detail.
Berkelium(III) chloride also known as berkelium trichloride, is a chemical compound with the formula BkCl3. It is a water-soluble green salt with a melting point of 603 °C. This compound forms the hexahydrate, BkCl3·6H2O.
Protactinium(V) bromide is an inorganic compound. It is a halide of protactinium, consisting of protactinium and bromine. It is radioactive and has a chemical formula of PaBr5, which is a red crystal of the monoclinic crystal system.
Samarium compounds are compounds formed by the lanthanide metal samarium (Sm). In these compounds, samarium generally exhibits the +3 oxidation state, such as SmCl3, Sm(NO3)3 and Sm(C2O4)3. Compounds with samarium in the +2 oxidation state are also known, for example SmI2.
Americium compounds are compounds containing the element americium (Am). These compounds can form in the +2, +3, and +4, although the +3 oxidation state is the most common. The +5, +6 and +7 oxidation states have also been reported.
Berkelium tetrafluoride is a binary inorganic compound of berkelium and fluorine with the chemical formula BkF4.
Californium(IV) oxide is a binary inorganic compound of californium and oxygen with the formula CfO
2.
Berkelium(III) oxide is a binary inorganic compound of berkelium and oxygen with the chemical formula Bk
2O
3.
Berkelium bromide is a bromide of berkelium, with the chemical formula BkBr3.
Curium(IV) oxide is an inorganic chemical compound of curium and oxygen with the chemical formula CmO2. Since all isotopes of curium are man-made, the compound does not occur in nature.
Einsteinium oxychloride is an inorganic chemical compound of einsteinium, oxygen, and chlorine with the chemical formula EsClO.
References
- ↑ Morss, Lester R.; Fuger, J.; Goffart, J.; Edelstein, N.; Shalimoff, G. V. (1 January 1987). "Enthalpy of formation and magnetic susceptibility of californium sesquioxide, Cf2O3". Journal of the Less Common Metals . 127: 251–257. doi:10.1016/0022-5088(87)90385-7. ISSN 0022-5088 . Retrieved 10 April 2023.
- ↑ Macintyre, Jane E. (23 July 1992). Dictionary of Inorganic Compounds. CRC Press. p. 2826. ISBN 978-0-412-30120-9 . Retrieved 10 April 2023.
- ↑ Copeland, J. C.; Cunningham, B. B. (1 March 1969). "Crystallography of the compounds of californium—II crystal structure and lattice parameters of californium oxychloride and californium sesquioxide". Journal of Inorganic and Nuclear Chemistry . 31 (3): 733–740. doi:10.1016/0022-1902(69)80020-5. ISSN 0022-1902 . Retrieved 10 April 2023.
- ↑ Green, J. L.; Cunningham, B. B. (1 September 1967). "Crystallography of the compounds of californium. I. Crystal structure and lattice parameters of californium sesquioxide and californium trichloride". Inorganic and Nuclear Chemistry Letters . 3 (9): 343–349. doi:10.1016/0020-1650(67)80040-0. ISSN 0020-1650 . Retrieved 10 April 2023.
- ↑ Schweitzer, George K.; Pesterfield, Lester L. (14 January 2010). The Aqueous Chemistry of the Elements. Oxford University Press. p. 406. ISBN 978-0-19-539335-4 . Retrieved 11 April 2023.
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