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Interchalcogen
The chalcogens react with each other to form interchalcogen compounds. Although no chalcogen is extremely electropositive,This article uses Pauling electronegativity throughout. nor quite as electronegative as the halogen fluorine (the most electronegative element), there is a large difference in electronegativity between the top (oxygen = 3.44 — the second most electronegative element after fluorine) and bottom (polonium = 2.0) of the group. Combined with the fact that there is a significant trend towards increasing metallic behaviour while descending the group (oxygen is a gaseous nonmetal, while polonium is a silvery post-transition metalThe classification of polonium as a post-transition metal or a metalloid is disputed.), this causes the interchalcogens to display many different kinds of bonding: covalent, ionic, metallic, and semimetallic.The heavier halogens are sufficiently electronegative to prevent ionic or metallic bonding in the interhalogens, and the lighter pnic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chalcogen
The chalcogens (ore forming) ( ) are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family. Group 16 consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and the radioactive elements polonium (Po) and livermorium (Lv). Often, oxygen is treated separately from the other chalcogens, sometimes even excluded from the scope of the term "chalcogen" altogether, due to its very different chemical behavior from sulfur, selenium, tellurium, and polonium. The word "chalcogen" is derived from a combination of the Greek word () principally meaning copper (the term was also used for bronze/brass, any metal in the poetic sense, ore or coin), and the Latinized Greek word , meaning ''born'' or ''produced''. Sulfur has been known since antiquity, and oxygen was recognized as an element in the 18th century. Selenium, tellurium and polonium were discovered in the 19th century, and livermorium in 2000. All of the chalcoge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioxygen
There are several known allotropes of oxygen. The most familiar is molecular oxygen (O2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O3). Others are: *Atomic oxygen (O1), a free radical. *Singlet oxygen (O2*), one of two metastable states of molecular oxygen. *Tetraoxygen (O4), another metastable form. * Solid oxygen, existing in six variously colored phases, of which one is and another one metallic. Atomic oxygen Atomic oxygen, denoted O(3P) or O(3P), is very reactive, as the single atoms of oxygen tend to quickly bond with nearby molecules. On Earth's surface, it exists naturally for a very short time. In outer space, the presence of ample ultraviolet radiation results in a low Earth orbit atmosphere in which 96% of the oxygen occurs in atomic form. Ryan D. McCulla, Saint Louis University (2010). /acswebcontent.acs.org/prfar/2010/reports/P11141.html "Atomic Oxygen O(3P): Phot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenium Trioxide
Selenium trioxide is the inorganic compound with the formula Se O3. It is white, hygroscopic solid. It is also an oxidizing agent and a Lewis acid. It is of academic interest as a precursor to Se(VI) compounds.Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier Preparation Selenium trioxide is difficult to prepare because it is unstable with respect to the dioxide: :2 SeO3 → 2 SeO2 + O2 It has been generated in a number of ways despite the fact that the dioxide does not combust under normal conditions. One method entails dehydration of anhydrous selenic acid with phosphorus pentoxide at 150–160 °C. Another method is the reaction of liquid sulfur trioxide with potassium selenate. :SO3 + K2SeO4 → K2SO4 + SeO3 Reactions In its chemistry SeO3 generally resembles sulfur trioxide, SO3, rather than tellurium trioxide, TeO3. At 120 °C SeO3 reacts with selenium dioxide to form the Se(VI)-Se(IV) compound diselenium pentaoxide:Z. Žák " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenium Dioxide
Selenium dioxide is the chemical compound with the formula SeO2. This colorless solid is one of the most frequently encountered compounds of selenium. Properties Solid SeO2 is a one-dimensional polymer, the chain consisting of alternating selenium and oxygen atoms. Each Se atom is pyramidal and bears a terminal oxide group. The bridging Se-O bond lengths are 179 pm and the terminal Se-O distance is 162 pm.Handbook of Chalcogen Chemistry: New Perspectives in Sulfur, Selenium and Tellurium, Franceso A. Devillanova, Royal Society of Chemistry, 2007, The relative stereochemistry at Se alternates along the polymer chain ( syndiotactic). In the gas phase selenium dioxide is present as dimers and other oligomeric species, at higher temperatures it is monomeric. The monomeric form adopts a bent structure very similar to that of sulfur dioxide with a bond length of 161 pm. The dimeric form has been isolated in a low temperature argon matrix and vibrational spectra indicate that it has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allotropes Of Sulfur
The element sulfur exists as many allotropes. In number of allotropes, sulfur is second only to carbon. Greenwood, 652 In addition to the allotropes, each allotrope often exists in polymorphs (different crystal structures of the same covalently bonded S molecules) delineated by Greek prefixes (α, β, etc.). Furthermore, because elemental sulfur has been an item of commerce for centuries, its various forms are given traditional names. Early workers identified some forms that have later proved to be single or mixtures of allotropes. Some forms have been named for their appearance, e.g. "mother of pearl sulfur", or alternatively named for a chemist who was pre-eminent in identifying them, e.g. "Muthmann's sulfur I" or "Engel's sulfur". Steudel, 17 The most commonly encountered form of sulfur is the orthorhombic polymorph of , which adopts a puckered ring – or "crown" – structure. Two other polymorphs are known, also with nearly identical molecular structures. Greenwood, 654 I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trisulfur
The molecule, known as trisulfur, sulfur trimer, thiozone, or triatomic sulfur, is a cherry-red allotrope of sulfur. It comprises about 10% of vaporised sulfur at and . It has been observed at cryogenic temperatures as a solid. Under ordinary conditions it converts to cyclooctasulfur. :8 S3 → 3 S8 Structure and bonding In terms of structure and bonding and ozone () are similar. Both adopt bent structures and are diamagnetic. Although represented with S=S double bonds, the bonding situation is more complex. The S–S distances are equivalent and are , and with an angle at the central atom of . However, cyclic , where the sulfur atoms are arranged in an equilateral triangle with three single bonds (similar to cyclic ozone and cyclopropane), is calculated to be lower in energy than the bent structure experimentally observed. The name thiozone was invented by Hugo Erdmann in 1908 who hypothesized that comprises a large proportion of liquid sulfur. However its existen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disulfur
Disulfur is the diatomic molecule with the formula S2. It is analogous to the dioxygen molecule but rarely occurs at room temperature. This violet gas is the dominant species in hot sulfur vapors. S2 is one of the minor components of the atmosphere of Io, which is predominantly composed of SO2. The instability of S2 is usually described in the context of the double bond rule. Synthesis This violet gas is generated by heating sulfur above 720 °C, comprising 99% of the vapor at low pressure (1 mm Hg) at 530 °C. Disulfur can be produced when an atmosphere of COS is irradiated with UV light using a mercury photosensitizer or when CS2, H2S2, S2Cl2 or C2H4S, PSF3 or COS are irradiated. Natural occurrence Gaseous disulfur has been detected emanating from the surface of Jupiter's moon Io, from the vicinity of Pele volcano. Properties The ground state of S2 is a triplet: a diradical, with two unpaired electrons like O2 and SO. It has the S-S bond length of 18 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Trioxide
Sulfur trioxide (alternative spelling sulphur trioxide, also known as ''nisso sulfan'') is the chemical compound with the formula SO3. It has been described as "unquestionably the most important economically" sulfur oxide. It is prepared on an industrial scale as a precursor to sulfuric acid. Sulfur trioxide exists in several forms - gaseous monomer, crystalline trimer, and solid polymer. Sulfur trioxide is a solid at just below room temperature with a relatively narrow liquid range. Gaseous SO3 is the primary precursor to acid rain. Molecular structure and bonding Monomer The molecule SO3 is trigonal planar. As predicted by VSEPR theory, its structure belongs to the D3h point group. The sulfur atom has an oxidation state of +6 and may be assigned a formal charge value as low as 0 (if all three sulfur-oxygen bonds are assumed to be double bonds) or as high as +2 (if the Octet Rule is assumed). When the formal charge is non-zero, the S-O bonding is assumed to be delocalized. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of copper extraction and the burning of sulfur- bearing fossil fuels. Structure and bonding SO2 is a bent molecule with ''C''2v symmetry point group. A valence bond theory approach considering just ''s'' and ''p'' orbitals would describe the bonding in terms of resonance between two resonance structures. The sulfur–oxygen bond has a bond order of 1.5. There is support for this simple approach that does not invoke ''d'' orbital participation. In terms of electron-counting formalism, the sulfur atom has an oxidation state of +4 and a formal charge of +1. Occurrence Sulfur dioxide is found on Earth and exists in very small concentrations and in the atmosphere at about 1 ppm. On other p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disulfur Dioxide
Disulfur dioxide, dimeric sulfur monoxide or SO dimer is an oxide of sulfur with the formula S2O2. The solid is unstable with a lifetime of a few seconds at room temperature. Structure Disulfur dioxide adopts a ''cis'' planar structure with ''C''2v symmetry. The S−O bond length is 145.8 pm, shorter than in sulfur monoxide. The S−S bond length is 202.45 pm and the O−S−S angle is 112.7°. S2O2 has a dipole moment of 3.17 D. It is an asymmetric top molecule. Formation Sulfur monoxide (SO) converts to disulfur dioxide (S2O2) spontaneously and reversibly. So the substance can be generated by methods that produce sulfur monoxide. Disulfur dioxide has also been formed by an electric discharge in sulfur dioxide. Another laboratory procedure is to react oxygen atoms with carbonyl sulfide or carbon disulfide vapour. Although most forms of elemental sulfur ( S8 and other rings and chains) do not combine with SO2, atomic sulfur does so to form sulfur monoxide, which d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Monoxide
Sulfur monoxide is an inorganic compound with formula . It is only found as a dilute gas phase. When concentrated or condensed, it converts to S2O2 ( disulfur dioxide). It has been detected in space but is rarely encountered intact otherwise. Structure and bonding The SO molecule has a triplet ground state similar to O2 and S2, that is, each molecule has two unpaired electrons. The S−O bond length of 148.1 pm is similar to that found in lower sulfur oxides (e.g. S8O, S−O = 148 pm) but is longer than the S−O bond in gaseous S2O (146 pm), SO2 (143.1 pm) and SO3 (142 pm). The molecule is excited with near infrared radiation to the singlet state (with no unpaired electrons). The singlet state is believed to be more reactive than the ground triplet state, in the same way that singlet oxygen is more reactive than triplet oxygen. Production and reactions Production of SO as a reagent in organic syntheses has centred on using compounds that "extrud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disulfur Monoxide
Disulfur monoxide or sulfur suboxide is an inorganic compound with formula S2O, one of the lower sulfur oxides. It is a colourless gas and condenses to give a roughly dark red coloured solid that is unstable at room temperature. occurs rarely in natural atmospheres, but can be made by a variety of laboratory procedures. For this reason, its spectroscopic signature is very well understood. Structure and spectrum Condensed solid S2O absorbs at (roughly indigo) and (roughly lime). These bands have been assigned to decomposition products S3 and S4. In the ultraviolet, S2O has absorption band systems in the ranges 250–340 nm and 190–240 nm. There are bands at 323.5 and 327.8 nm. The band in the 315–340 nm range is due to the transition. Gaseous disulfur monoxide does not absorb in the visible spectrum. The microwave spectrum of S2O has the following rotational parameters: ''A'' = 41915.44 MHz, ''B'' = 5059.07 MHz, and ''C''&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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