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Californium(III) Polyborate
Californium polyborate is a covalent compound with formula Cf 6O8(OH)5 In this compound the californium is in a +3 oxidation state. This compound is the highest atomic number borate with a visible solid phase. Heavier elements than californium decay too fast to make macroscopic amounts of solid crystals. Californium polyborate is unusual in that californium is covalently bound to the borate. Californium was expected to resemble lanthanide elements in being highly ionic. The polyborate anion is polarisable and flexible. The 5f, 6d, 7s, and 7p orbitals of californium are all involved on the bonding. Most valence electrons are in the 5f orbital, and a significant fraction () in the 6d orbital, and smaller fractions of one electron are in the 7s and 7p orbitals. Formation Californium(III) polyborate can be made by autoclaving a californium(III) chloride solution in water with excess boric acid for a week at 240°C. This is then cooled slowly to room temperature for another three day ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Square Antiprismatic Molecular Geometry
In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ..., the square antiprismatic molecular geometry describes the shape of chemical compound, compounds where eight atoms, groups of atoms, or ligands are arranged around a central atom, defining the vertices of a square antiprism. This shape has D4d molecular symmetry, symmetry and is one of the three common shapes for octacoordinate transition metal complexes, along with the dodecahedral molecular geometry, dodecahedron and the bicapped trigonal prismatic molecular geometry, bicapped trigonal prism. Like with other high coordination numbers, eight-coordinate compounds are often distorted from idealized geometries, as illustrated by the structure of Na3TaF8. In this case, with the small Na+ ions, lattice energy, lattice force ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Californium
Californium is a radioactive chemical element with the symbol Cf and atomic number 98. The element was first synthesized in 1950 at Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory), by bombarding curium with alpha particles ( helium-4 ions). It is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all elements that have been produced in amounts large enough to see with the naked eye (after einsteinium). The element was named after the university and the U.S. state of California. Two crystalline forms exist for californium at normal pressure: one above and one below . A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. Californium compounds are dominated by the +3 oxidation state. The most stable of californium's twenty known isotopes is californium-251, with a half-life of 898 years. This short half-life means the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanthanide
The lanthanide () or lanthanoid () series of chemical elements comprises the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. These elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare-earth elements or rare-earth metals. The informal chemical symbol Ln is used in general discussions of lanthanide chemistry to refer to any lanthanide. All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell. There is some dispute on whether lanthanum or lutetium is a d-block element, but lutetium is usually considered so by those who study the matter; it is included due to its chemical similarities with the other 14. All lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium. These elements are called lanthanides because the eleme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyborate
A borate is any of several boron oxyanions, negative ions consisting of boron and oxygen, such as orthoborate , metaborate , or tetraborate ; or any salt with such anions, such as sodium metaborate, and disodium tetraborate . The name also refers to certain functional groups in molecules consisting of boron and oxygen, and esters with such groups, such as triethyl orthoborate . Natural occurrence Borate ions occur, alone or with other anions, in many borate and borosilicate minerals such as borax, boracite, ulexite (boronatrocalcite) and colemanite. Borates also occur in seawater, where they make an important contribution to the absorption of low frequency sound in seawater. Borates also occur in plants, including almost all fruits. Anions The main borate anions are: * tetrahydroxyborate , found in sodium tetrahydroxyborate . * orthoborate , found in trisodium orthoborate * perborate , as in sodium perborate * metaborate or , found in sodium metaborate * diborate , f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Californium(III) Chloride
Californium(III) chloride is an inorganic compound with a chemical formula CfCl3. Like in californium oxide (Cf2O3) and other californium halides, including californium fluoride (CfF3) and iodide (CfI3), the californium atom has an oxidation state of +3. Preparation Californium(III) chloride can prepared by reacting californium(III) oxide with hydrogen chloride. :Cf2O3 + 6 HCl → 2 CfCl3 + 3 H2O Properties Chemical properties When heating californium(III) chloride until 500 °C, it can hydrolyse to produce californium oxychloride. Physical properties Californium(III) chloride is soluble in water, giving Cf3+ and Cl− ions. This salt has an emerald-green color. Its crystal structure is hexagonal. It is strongly radioactive. See also * Californium * Californium compounds 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 (stron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curium
Curium is a transuranium element, transuranic, radioactive decay, radioactive chemical element with the chemical symbol, symbol Cm and atomic number 96. This actinide element was named after eminent scientists Marie Curie, 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 Lawrence Berkeley National Laboratory, Berkeley. They bombarded the newly discovered element plutonium (the isotope plutonium-239, 239Pu) 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 contain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
α Particles
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways. Alpha particles are named after the first letter in the Greek alphabet, α. The symbol for the alpha particle is α or α2+. Because they are identical to helium nuclei, they are also sometimes written as or indicating a helium ion with a +2 charge (missing its two electrons). Once the ion gains electrons from its environment, the alpha particle becomes a normal (electrically neutral) helium atom . Alpha particles have a net spin of zero. Due to the mechanism of their production in standard alpha radioactive decay, alpha particles generally have a kinetic energy of about 5 MeV, and a velocity in the vicinity of 4% of the speed of light. (See discussion below for the limits of these figures in alpha decay.) They a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Rays
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz (), it imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation ''gamma rays'' based on their relatively strong penetration of matter; in 1900 he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power. Gamma rays from radioactive decay are in the energy range from a few kiloelectronvolts ( keV) to approximately 8 megaelectronvolts ( MeV), corresponding to the typical energy levels in nuclei with reasonably long lifeti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutrons
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus, and each has a mass of approximately one atomic mass unit, they are both referred to as nucleons. Their properties and interactions are described by nuclear physics. Protons and neutrons are not elementary particles; each is composed of three quarks. The chemical properties of an atom are mostly determined by the configuration of electrons that orbit the atom's heavy nucleus. The electron configuration is determined by the charge of the nucleus, which is determined by the number of protons, or atomic number. The number of neutrons is the neutron number. Neutrons do not affect the electron configuration, but the sum of atomic and neutron numbers is the mass of the nucleus. Atoms of a chemical element that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Californium Compounds
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. The +3 oxidation state is represented by californium(III) oxide (yellow-green, Cf2O3), californium(III) fluoride (bright green, CfF3) and californium(III) iodide (lemon yellow, CfI3). Other +3 oxidation states include the sulfide and metallocene. Californium(IV) oxide (black brown, CfO2), californium(IV) fluoride (green, CfF4) represent the IV oxidation state. The II state is represented by californium(II) bromide (yellow, CfBr2) and californium(II) iodide (dark violet, CfI2). Compounds Californ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
