|
Radium Compounds
Radium compounds are compounds containing the element radium (Ra). Due to radium's radioactivity, not many compounds have been well characterized. Solid radium compounds are white as radium ions provide no specific coloring, but they gradually turn yellow and then dark over time due to self-radiolysis from radium's alpha decay.Kirby et al., p. 4 Insoluble radium compounds coprecipitate with all barium, most strontium, and most lead compounds.Kirby et al., p. 8 Oxides and hydroxides Radium oxide (RaO) has not been characterized well past its existence, despite oxides being common compounds for the other alkaline earth metals. Radium hydroxide (Ra(OH)2) is the most readily soluble among the alkaline earth hydroxides and is a stronger base than its barium congener, barium hydroxide.Kirby et al., pp. 4–8 It is also more soluble than actinium hydroxide and thorium hydroxide: these three adjacent hydroxides may be separated by precipitating them with ammonia. Halides Radium fluo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radium
Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather than oxygen) upon exposure to air, forming a black surface layer of radium nitride (Ra3N2). All isotopes of radium are radioactive, the most stable isotope being radium-226 with a half-life of 1600 years. When radium decays, it emits ionizing radiation as a by-product, which can excite fluorescent chemicals and cause radioluminescence. Radium, in the form of radium chloride, was discovered by Marie and Pierre Curie in 1898 from ore mined at Jáchymov. They extracted the radium compound from uraninite and published the discovery at the French Academy of Sciences five days later. Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1911. In nature, radium is found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Radiation
Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into a different atomic nucleus, with a mass number that is reduced by four and an atomic number that is reduced by two. An alpha particle is identical to the nucleus of a helium-4 atom, which consists of two protons and two neutrons. It has a charge of and a mass of . For example, uranium-238 decays to form thorium-234. While alpha particles have a charge , this is not usually shown because a nuclear equation describes a nuclear reaction without considering the electrons – a convention that does not imply that the nuclei necessarily occur in neutral atoms. Alpha decay typically occurs in the heaviest nuclides. Theoretically, it can occur only in nuclei somewhat heavier than nickel (element 28), where the overall binding energy per nucleon is no longer a maximum and the nuclides are therefore unstable toward spontaneo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrafluoroberyllate
Tetrafluoroberyllate or orthofluoroberyllate is an anion containing beryllium and fluorine. The fluoroanion has a tetrahedral shape, with the four fluorine atoms surrounding a central beryllium atom. It has the same size and outer electron structure as sulfate. Therefore, many compounds that contain sulfate have equivalents with tetrafluoroberyllate. Examples of these are the langbeinites, and Tutton's salts. Properties The Be–F bond length is between 145 and 153 pm. The beryllium has sp3 atomic hybridization, leading to a longer bond than in BeF2, where the Be is sp hybridized. In trifluoroberyllates, there are actually BeF4 tetrahedra arranged in a triangle, so that three fluorine atoms are shared on two tetrahedra each, resulting in a formula of Be3F9. In the tetrafluoroberyllates, the tetrahedra can rotate to various degrees. At room temperature, they are hindered from moving. But as temperature increases, they can rotate around the threefold axis, (ie a line through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodate
An iodate is the polyatomic anion with the formula . It is the most common form of iodine in nature, as it comprises the major iodine-containing ores. Iodate salts are often colorless. They are the salts of iodic acid. Structure Iodate is pyramidal in structure. The O–I–O angles range from 97° to 105°, somewhat smaller than the O–Cl–O angles in chlorate. Reactions Redox Iodate is one of several oxyanions of iodine, and has an oxidation number of +5. It participates in several redox reactions, such as the iodine clock reaction. Iodate show no tendency to disproportionate to periodate and iodide, in contrast to the situation for chlorate. Iodate is reduced by sulfite: :6HSO3- + 2IO3- -> 2I- + 6HSO4- Iodate oxidizes iodide: :5I- + IO3- + 3H2SO4 -> 3I2 + 3H2O + 3SO4^2- Similarly, chlorate oxidizes iodide to iodate: :I- + ClO3- -> Cl- + IO3- Iodate is also obtained by reducing a periodate with a sulfide. The byproduct of the reaction is a sulfoxide. Acid-base Iod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromate And Dichromate
Chromate salts contain the chromate anion, . Dichromate salts contain the dichromate anion, . They are oxyanions of chromium in the +6 oxidation state and are moderately strong oxidizing agents. In an aqueous solution, chromate and dichromate ions can be interconvertible. Chemical properties Potassium-chromate-sample.jpg, potassium chromate Potassium-dichromate-sample.jpg, potassium dichromate Chromates react with hydrogen peroxide, giving products in which peroxide, , replaces one or more oxygen atoms. In acid solution the unstable blue peroxo complex Chromium(VI) oxide peroxide, CrO(O2)2, is formed; it is an uncharged covalent molecule, which may be extracted into ether. Addition of pyridine results in the formation of the more stable complex CrO(O2)2py. Acid–base properties In aqueous solution, chromate and dichromate anions exist in a chemical equilibrium. :2 + 2 H+ + H2O The predominance diagram shows that the position of the equilibrium depends on b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radium Sulfate
Radium sulfate (or radium sulphate) is an inorganic compound with the formula RaSO4 and an average molecular mass of 322.088 g/mol. This salt is the least soluble of all known sulfate salts. It was formerly used in radiotherapy and smoke detectors, but this has been phased out in favor of less hazardous alternatives. Properties Radium sulfate crystallises in a solid in the same structure as barium sulfate. It forms crystals in the orthorhombic crystal system, with a unit cell of dimensions ''a'' = 9.07 ''b''=5.52 and ''c'' = 7.28 Å. The unit cell volume is 364 Å3. Distance from the radium ion to oxygen is 2.96 Å and the sulfur to oxygen bond length in the sulfate ion is 1.485 Å. In this compound the ionic radius of the radium ion is 1.66 Å, and it is in ten coordination. Radium sulfate can form solid solutions with the sulfates of strontium, barium or lead. References {{radium compounds Radium compounds Sulfates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitric Acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitric acid has a concentration of 68% in water. When the solution contains more than 86% , it is referred to as ''fuming nitric acid''. Depending on the amount of nitrogen dioxide present, fuming nitric acid is further characterized as red fuming nitric acid at concentrations above 86%, or white fuming nitric acid at concentrations above 95%. Nitric acid is the primary reagent used for nitration – the addition of a nitro group, typically to an organic molecule. While some resulting nitro compounds are shock- and thermally-sensitive explosives, a few are stable enough to be used in munitions and demolition, while others are still more stable and used as pigments in inks and dyes. Nitric acid is also commonly used as a strong oxidizing agen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radium Carbonate
Radium carbonate is a compound of radium, carbon, and oxygen. This salt is a poisonous, radioactive, Amorphous solid, amorphous, white powder that is used in medicine. It is notable for being more soluble than barium carbonate, unlike other Radium#Compounds, radium compounds. Even though it is insoluble in water, it is soluble in dilute acids and concentrated ammonium carbonate. Preparation Radium carbonate can be produced by using Ra2+ ions and carbonate:Richard C. Ropp. Encyclopedia of the Alkaline Earth Compounds. Elsevier, 2013. pp 370-371. Radium Carbonate :Ra2+ + CO32- → RaCO3 Because of the very low solubility of this salt, it will form a white precipitate. Reactions Radium carbonate can be used to produce radium nitrate and other radium salts: :RaCO3 + 2HNO3 → Ra(NO3)2 + H2O + CO2 References Radium compounds Carbonates {{Inorganic-chemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radium Nitrate
Radium nitrate is a radioactive salt with the formula Ra(NO3)2. It is a white solid, but old samples appear yellowish-grey. It has a lower solubility than barium nitrate. It decomposes at 280 °C to radium oxide. Production Radium nitrate is produced by the reaction of radium carbonate or radium sulfate with nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...: :RaCO3 + HNO3 → Ra(NO3)2 + CO2 + H2O References Radium compounds Nitrates {{Chem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling and melting point are the lowest among all the elements. It is the second lightest and second most abundant element in the observable universe (hydrogen is the lightest and most abundant). It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and in Jupiter, due to the very high nuclear binding energy (per nucleon) of helium-4, with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. The most common isotope of helium in the universe is helium-4, the vast majority of which was formed during t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Particle
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 are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colorless and odorless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins), in the nucleic acids ( DNA and RNA) and in the energy transfer molecule adenosine triphosphate. The human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes the movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere. Many indus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> Radium")
