problem of bonding in the uranium nitrides

by N. Segal

Publisher: Atomic Energy Board in Pretoria

Written in English
Published: Pages: 16 Downloads: 67
Share This

Subjects:

  • Uranium nitride.

Edition Notes

Includes bibliographical references.

Statementby N. Segal [and] F. Sebba.
SeriesPEL 165
ContributionsSebba, F. 1912-
Classifications
LC ClassificationsQD181.U7 S45
The Physical Object
Pagination16 p.
Number of Pages16
ID Numbers
Open LibraryOL5729625M
LC Control Number70504634

Bunce, who was a county commissioner during the uranium boom, spoke with Steve Guttman and John Donnely. Subjects: jobs, problems as county commissioner, new jobs in uranium boom, bonds, current problems in Moab, future of Moab, Moab in , penny stocks, lumber business, growth of Moab, accidents (47 pages). Uranium in body fluids generally exists as the uranyl ion (UO2)2+ complexed with anions, such as citrate and bicarbonate, or plasma proteins. Uranium preferentially distributes to bone, liver, and kidney. The large majority of uranium that enters the body is not absorbed and is eliminated from the body via the urine and faeces. Toxicity Values. An example of Van der Waal bond is the hydrogen bond between hydrogen and oxygen, which is responsible for many properties of water. In polymers, there are covalent bonds between the atoms of the polymer, but the polymeric macromolecules (or chains) are kept together by Van der Waals forces. Very quickly, however, the uranium nitride reacts with a neighbouring C-H bond of one of the adjacent ligands. ’Interestingly, the observed carbon-hydrogen bond activation is strikingly.

  Chances are uranium nitride reacts with methane, because it has proved itself reactive with carbon-hydrogen bonds. “Clearly uranium nitrides are reactive, so this raises the question, what else do they react with?” says Kiplinger. “If it could react with a carbon-hydrogen bond in an added substrate, for example methane, then that would be a really exciting reaction,” she says. THE existence of three uranium nitrides, UN, U2N3, and UN2, has been well established, but few thermo­ dynamic and thermochemical properties have been reported. Recent redeterminations of the melting point of uranium mononitride have raised the previously reported melting temperature to 28s0°C at . Cleaving the strong triple bond in N 2 is r, the fixation of dinitrogen is important both in nature and in the chemical industry, where the Haber–Bosch process is used on a huge scale to convert N 2 to ammonia. While this industrial process uses an iron-based catalyst and harsh conditions, biological systems use multimetallic clusters for dinitrogen fixation under ambient. Hydrogen Bond Donor Count: 0: Computed by Cactvs (PubChem release ) Hydrogen Bond Acceptor Count: 1: Computed by Cactvs (PubChem release ) Rotatable Bond Count: 0: Computed by Cactvs (PubChem release ) Exact Mass: g/mol: Computed by PubChem (PubChem release

  The bonding type is a set of six covalent bonds, not ionic. The following is an extract from the Inorganic Chemistry, part of the ACS (American Chemistry Association): “The electron density distribution of [PPh4]UF6 has been experimentally determi. Naturally occurring uranium consists of 99% uranium and 1% uranium Uranium is the only naturally occurring fissionable fuel (a fuel that can sustain a chain reaction). Uranium fuel used in nuclear reactors is enriched with uranium The chain reaction is carefully controlled using neutron-absorbing materials. Evans and his team are now looking at ways to transform these compounds into pure UN, which could be used as nuclear fuel. ’One target is to convert the remaining four azide ions in the atom U 8 N. Naturally occurring uranium is composed of three major isotopes, uranium (% natural abundance), uranium (%), and uranium (%). All three isotopes are radioactive, creating radioisotopes, with the most abundant and stable being uranium with a half-life of ×10 9 years (close to the age of the Earth), uranium with a half-life of ×10 8 years, and uranium.

problem of bonding in the uranium nitrides by N. Segal Download PDF EPUB FB2

Data pertaining to terminal uranium nitrides are limited to the spectroscopic observation of the binary uranium nitrides UN and NUN and the ternary nitride NUF[subscript 3] under matrix conditions.

We are interested in the uranium nitride functional group as it incorporates metal-ligand multiple bonding, valence f orbitals, and redox by: multiple bonds concerning U=O, U=N,6,9, and U=E (E = S, Se, Te)12,42 have been investigated with great interest.

Furthermore recent developments into U=C multiple bonds means they now represent a burgeoning field of research, However, due to the prominent paucity of reports of formal U≡N triple bonds in uranium nitrides. The chemical bonding nature of uranium nitrides has been analyzed by the study of the valence charge density.

The results of Lu et al. [90], [91] showed that there is a spherical distribution of charge around the uranium and nitrogen atoms in the UN, and there is a slight deformation of the charge distribution between the nearest by: 3. Books. Publishing Support.

Login. cohesive energy and bulk modulus of the crystalline uranium nitrides UN, The mixed metallic-covalent chemical bonding is found both in LCAO calculations of UN and U 2 N 3 crystals; UN 2 crystal has the semiconducting nature.

Export citation and abstract BibTeX by: Bridger, N J, Dell, R M, and Wheeler, V J. OXIDATION AND HYDROLYSIS OF URANIUM AND PLUTONIUM y unknown/Code not available: N. p., Web. uranium compounds. Among those Actinide nitrides, uranium nitrides are typical example of them, and numerous experimental and theoretical works focushave ed on them.

The physical and chemical properties of uranium nitrides such as the reactivity features, electronic structure, lattice dynamics, surface properties, structural phase. with uranium nitrides but not relevant for the uranium-free.

trogen in the bonding gas, They will appear in book form and are expected to be available in late andrespectively. A straightforward oxidation strategy affords the first pentavalent uranium carbene complex, 2.

Owing to the structural similarity of 1 and 2, it was possible for the first time to directly probe the differences in U C bonding on oxidation of U IV to U V. Some problems in nonstoichiometry of α-uranium sesquinitride.

Journal of Alloys and CompoundsStructure and bonding in metal-rich compounds: Pnictides, chalcides and halides. Structure Investigations of Two Uranium Nitrides U2N3+x.

physica status solidi (b)21 (1). Chemical reactions of carbides, nitrides, and diborides of titanium and zirconium and chemical bonding in these compounds Chemical reactions of titanium and zirconium carbides, nitrides, and diborides and chemical bonding in these compounds.

Document ID. nium nitrides. The only reports of terminal uranium nitrides pertain to UN, NUN, and UNF 3 prepared under matrix isolation conditions at 4 K (9–11) and the [NUO]+ cation observed with mass spectrom-etry (12, 13). Molecular uranium nitride com-plexes that have been isolated under ambient conditions in exploitable quantities exclusively.

Print book: Fiction: International government publication: Juvenile audience: EnglishView all editions and formats: Rating: (not yet rated) 0 with reviews - Be the first. Subjects: Uranium compounds -- Bibliography.

Uranium compounds. More like this: Similar Items. the reaction between uranium hydride and ammonia at room temperature Journal Article Alei, M - Journal of Physical Chemistry (U.S.) The reaction between NH/sub 3/ and UH/sub 3/ at room temperature was found to proceed very rapidly to form essentially a monolayer of nitride.

uranium. Better agreement with experiment is observed with SP calculations. Note that these calculations merely point out to the trend of developing magnetization from present PAW-GGA calculations, i.e. they do not point to the long range magnetic order or the ground state.

In fact UO 2 in which uranium is also tetravalent is known to. Terminal uranium nitrides have so far proven impossible to isolate by photolysis of azides. Here we report the second ever example of an isolated terminal uranium(VI) nitride. We show that the terminal nitride [NBu4][U(OSi(OtBu)3)4(N)], 3, can be prepared upon photolysis with UV light of the U(IV) azide analogue.

This is achieved by careful tailoring of the azide precursor and of the reaction. Note: Citations are based on reference standards. However, formatting rules can vary widely between applications and fields of interest or study. The specific requirements or preferences of your reviewing publisher, classroom teacher, institution or organization should be applied.

Magnetic communication between uranium centers can provide important information on the nature of bonding 5b,7a,8f,16 and lead to attractive magnetic properties. 17 Examples of unambiguous magnetic coupling are rare in uranium chemistry and mostly limited to antiferromagnetic coupling between uranium(v) centers with values of χ maximum in the.

Lastly, we note that the σ-bonding component of the U IV NU IV and Th IV NTh IV (9 − is depicted in Fig. 7) bonds reported here are higher in energy than the two π-contributions. 18 This scenario is usually only observed in terminal uranium nitrides and uranyl with short UN and UO bonds.

9,11 Why this is the case here, and whether this is. Such alkaline or alkaline earth metal nitrides as Li 3 N, Ca 3 N 2 and Sr 3 N 2 have the ionic bonding between metal and nitrogen, and the covalent bonding mainly contributes to the main group nitrides as BN, AlN and Si 3 N 4.

Transition metal nitrides are so–called interstitial compounds having metallic bonding character. There exist many problems between ceramic and metal materials, such as the atom bond configuration, chemical and physical properties, etc. These problems make the joining of ceramics to metals difficult.

The following main problems such as ionic bonds and covalent bonds are characteristic atomic bond configurations of ceramic materials. Uranium nitrides are denser and more stable, and conduct heat better than mixed uranium-plutonium oxide fuels – properties that suggest the fuels could run cooler in.

Electronic structure of crystalline uranium nitrides UN, U 2 N 3 and UN 2: LCAO calculations with the basis set optimization. R A Evarestov 1, A I Panin 1, A V Bandura 1 and M V Losev 1.

Published under licence by IOP Publishing Ltd. Although percent of the uranium in the ore is extracted during processing (thus reducing uranium concentrations by at least an order of magnitude), most of the uranium decay products (e.g., Th, Ra, Rn), which may comprise the majority of the total radioactivity of the ore, stay in the tailings (Hebel et al.,Van Metre.

Natural Bond Order analyses indicate that upon oxidation from uranium(IV) to (V) to (VI) the uranium contribution to the U═C σ-bond can increase from ca.

18 to 32% and within this component the. Unusual structure, bonding, and properties may provide a new possibility for a californium borate A new method to help solve the problem of nuclear waste.

Uranium nitrido derivatives. Recently, there have been many developments in the synthesis of complexes with terminal uranium nitride (–U≡N) bonds. In addition to radioactive concerns common to all uranium chemistry, production of uranium nitrido complexes has been slowed by harsh reaction conditions and solubility challenges.

Ceramic composition and properties, atomic and molecular nature of ceramic materials and their resulting characteristics and performance in industrial applications.

Industrial ceramics are commonly understood to be all industrially used materials that are inorganic, nonmetallic solids. Usually they are metal oxides (that is, compounds of metallic elements and oxygen), but many ceramics.

The uranium nitride used in the experiment was made by arc-melting uranium as a consumable electrode under 20 atmospheres of nitrogen. The resulting casting was heat-treated at °C in a vacuum of approximately 0. 1 N/m2 ( torr) to decompose any higher nitrides.

Sb, W and Cd. Uranium metal powder is autopyrophoric and can burn spontaneously at room temperature in the presence of air, oxygen and water. At − C uranium powder may self-ignite in atmospheres of CO 2 and N 2.

Oxidation of uranium under certain conditions may generate sufficient energy to cause a chemical explosion [4, 12, 35]. The paper I'll discuss briefly in this post is this one: Molten uranium dioxide structure and dynamics.

(Skinner et al Science Vol. Issuepp. ()) The famous "Elephants Foot" produced by the melting of the Chernobyl nuclear reactor in consists of a mixture of steel graphite, silicates produced by melting concrete and about 10% uranium dioxide which also melted during.

Uranium nitrides are usually prepared by mixing dinitrogen or ammonia with uranium under high temperatures and pressures. the nature and extent of the covalency in the chemical bonding .Uranium is a chemical element with the symbol U and atomic number It is a silvery-grey metal in the actinide series of the periodic table.A uranium atom has 92 protons and 92 electrons, of which 6 are valence m is weakly radioactive because all isotopes of uranium are unstable; the half-lives of its naturally occurring isotopes range betweenyears and billion years.Research led by Dr Steve Liddle has resulted in publication of the first uranium-nitrogen triple bond, which has eluded scientists for decades, in the leading journal Science.

Molecules which contain multiple bonds between a metal and elements such as carbon, nitrogen, and oxygen have attracted intense interest over many years. This is due to interest in their bonding, and the fact that such.