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Topic: Transition metal


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  Transition metal - Wikipedia, the free encyclopedia
The (loosely defined) transition metals are the 40 chemical elements 21 to 30, 39 to 48, 71 to 80, and 103 to 112.
Later transition metals have a stronger attraction between protons and electrons (since there are more of each present), which then would require more energy to remove the electrons.
Transition metals form good homogeneous or heterogeneous catalysts, for example iron is the catalyst for the Haber process.
en.wikipedia.org /wiki/Transition_metal   (1240 words)

  
 transition metal - Hutchinson encyclopedia article about transition metal   (Site not responding. Last check: 2007-10-21)
Any of a group of metallic elements that have incomplete inner electron shells and exhibit variable valency – for example, cobalt, copper, iron, and molybdenum.
The precious metals, gold, platinum, and silver are also transition metals.
Transition metals and their compounds are often used in industry as catalysts.
encyclopedia.farlex.com /transition+metal   (193 words)

  
 Transition metal   (Site not responding. Last check: 2007-10-21)
However, many interesting properties of the transition elements as a group are the result of their ability to contribute valence electrons from s orbitals before d orbitals, a property which all members of the d-block except zinc and scandium share, so the more restricted definition is in many contexts the more useful.
Similarly, zinc is not a transition metal in the stricter sense because its only ion, Zn, has a full d orbital, which does not participate in bonding.
The transition metals show such a range of oxidation states because their partially filled d orbitals can accept or donate electrons in chemical reactions.
transition-metal.ask.dyndns.dk   (1281 words)

  
 Transition metal salt complexes of polyamino organic compounds - Patent 4337335
Described are transition metal salt complexes of available neighboring amino and hydroxyl group pairs in polyamino organic compounds, their preparation, and use as intermediates in the preparation of selectively N-blocked polyamino organic compounds.
In the latter case, the transition metal cation is removed by the preferential formation of a complex with ammonium hydroxide which is soluble in ammonium hydroxide and water.
When removing the transition metal cation, hydrogen sulfide is a precipitating reagent of choice since it is a simple procedure to merely bubble hydrogen sulfide through the reaction mixture; also, the resulting transition metal sulfide is completely precipitated in a short period of time and is easily removed by filtration.
www.freepatentsonline.com /4337335.html   (12685 words)

  
 Kids.net.au - Encyclopedia Transition metal -   (Site not responding. Last check: 2007-10-21)
Main group elements prior to the appearance of the transition group elements in the periodic chart (ie, elements number 1 through 20) have no electrons in d orbitals, but only in the s and p orbitals.
Compared to Group II elements such as calcium, transition elements form ions with a wide variety of oxidation states.
The complex formed by the d block element zinc (though not strictly a transition element) is colourless, because the 3d orbitals are full - no electrons are able to move up to the higher group.
www.kidsseek.com /encyclopedia-wiki/tr/Transition_metal   (1047 words)

  
 The Achim Lab - Supramolecular Assemblies Containing Transition Metal Ions
Structures containing transition metal ions are of particular interest because of special magnetic and electric properties conferred upon the supramolecular assemblies by the presence of multiple metal paramagnetic centers.
Metal ions have been used for "programmed" reading of the information contained in ligands with multiple coordination sites, which is essential for directing the organization of elaborate structures in self-assembly processes.
The spatial arrangement and dimensions of the nanostructures is determined by the coordination properties of transition metal ions and by the structure of PNA, a synthetic analogue of DNA.
www.chem.cmu.edu /groups/achim/research/supra.html   (463 words)

  
 Chemical Elements.com - Transition Metals
The 38 elements in groups 3 through 12 of the periodic table are called "transition metals".
As with all metals, the transition elements are both ductile and malleable, and conduct electricity and heat.
The interesting thing about transition metals is that their valence electrons, or the electrons they use to combine with other elements, are present in more than one shell.
www.chemicalelements.com /groups/transition.html   (110 words)

  
 Transition metal -   (Site not responding. Last check: 2007-10-21)
More strictly, IUPAC defines the transition metals as any element with an incomplete d subshell or that may form stable ions only with an incomplete d subshell (IUPAC definition).
However, many interesting properties of the transition elements as a group are the result of their partly filled subshells from d orbitals, a property which all members of the d-block except zinc, cadmium and mercury share.
The (loosely defined) transition metals are the forty chemical elements 21 to 30, 39 to 48, 71 to 80, and 103 to 112.
psychcentral.com /psypsych/Transition_metal   (1331 words)

  
 Is Silver a Heavy Metal? | Silver: A Transition Element | Heavy Metals Article   (Site not responding. Last check: 2007-10-21)
Heavy metals were redefined based on a gram atomic weight, and also by the atomic number on the periodic table (with many variations in "opinion" of the starting number).
These acquired the name heavy metals because they all have high densities, but the usefulness of the term is related to their chemistry, not their density.
The term heavy metal is not truly a scientific term, and there has never been consensus on the meaning of this term in the scientific community.
www.silvermedicine.org /silver-heavy-metal.html   (823 words)

  
 Complex Ions and Coordination Compounds
The chemical and physical properties of the transition metal atoms and elements do not change periodically across a period as much as the representative atoms and elements of the same period.
Transition metal ions are Lewis Acids which tend to form stable Lewis Acid-Base adducts with Lewis Bases.
The color in these species is due to electronic transitions involving d-electrons, and the energies of these transitions are related to the ligands, the oxidation.state of the transition metal atom, and the n value in ns
www.sonoma.edu /users/b/brooks/115b/complex.html   (1364 words)

  
 Intro to Transition Metal Carbides
The catalytic uses of the transition metal carbides are mentioned in the context of this project because the low-temperature precursor methods reported in Chapter 9 have the potential for yielding high-surface area carbides possibly useful for catalytic applications.
One much-noted feature of the structure of the transition metal carbides is that the lattice adopted by the metal in the carbide is never that of the parent metal.
In contrast, the transition metal carbides are conductors with a shiny metallic and colored appearance and are hydrolytically stable.
www.ropine.com /chapter8.html   (5923 words)

  
 Transition-Metal Physics
Transition metals, especially 3d transition metals such as Fe, Ni and Cu are ubiquitous in IC production lines.
It is well known that 3d transition metals dissolved in silicon introduce deep energy levels in the band gap and act as generation-recombination centers, which reduce minority carrier lifetime, degrade the microchip devices, and give severe reliability problems.
Utzig [14] estimated the elastic component of the diffusion coefficient of 3d metals in Si and obtained results surprisingly close to the experimental data for the majority of transition metals, with the exception of the ionized copper Cu, whose ionic radius was so small that Utzig's model predicted a zero diffusion barrier for it.
www.mse.berkeley.edu /groups/weber/research/si_phys.html   (1371 words)

  
 ChemCases: Cisplatin - 6. Transition Metal Chemistry
The transition metals, also called the d-block elements, are found in groups 3-12 of the periodic table.
In addition to making the third row transition metals smaller, the lanthanide contraction also makes them less reactive because the valence electrons are relatively close to the nucleus and not available for chemical reactions.
Transition metals are excellent Lewis acids and accept electron density from many molecules or ions that act as Lewis bases; when a Lewis base donates its electron pair to a Lewis acid, it is said to coordinate to the Lewis acid and form a coordinate covalent bond.
chemcases.com /cisplat/cisplat06.htm   (2229 words)

  
 Transition Metal Catalysts
The transition metals are the group of metals in the middle section of the periodic table.
Many of the transition metals behave as catalysts, either as the metal itself or as a compound.
Transition metal catalysts are either homogeneous catalysts or heterogeneous catalysts.
www.sky-web.pwp.blueyonder.co.uk /Science/transitionmetalcatalysts.htm   (581 words)

  
 The Periodic Table of Transition Metals and Metal Clusters
Transition metal clusters are produced in an ultra high vacuum chamber by
Metal cluster ions are produced by sputtering, using (typically) a 10 mA
The cluster beam is bent by 10 degrees in
www.sci.ccny.cuny.edu /~lombardi/periodi.htm   (239 words)

  
 DETECTION OF DIVALENT TRANSITION METAL IONS IN COMPLEX MEDIA BY CAPILLARY ELECTROPHORESIS
The fungus precipitated the metal on and in the mycelia (Crusberg, et al., 1991).
Note that none of the peaks in the 30-second injection are baseline-resolved, and the "window" for the transition metal peaks goes from 1.9 minutes with the 30-second injection to 3.2 minutes with the 5-second injection.
Metal Ion Capillary Electrophoresis with Direct UV Detection Effect of a Charged Surfactant on the Migration Behavior of Metal Chelates, J. Chromatogr.
www.engg.ksu.edu /HSRC/97Proceed/Analytical2/detection.html   (1693 words)

  
 Quantum Chemistry   (Site not responding. Last check: 2007-10-21)
Transition metal complexes can absorb light and undergo electronic transitions.There are two rules that govern the electronic transitions.
It states that electronic transition of an ion in a centrosymmetric environment must be accompanied by a change in parity i.e.
In other words for a symmetric complex, electronic transitions with parities of type g»u and u»g are allowed, but that of g»g is forbidden.
www-users.york.ac.uk /~srms500/siti.org.uk/notes/transition_metals.html   (241 words)

  
 TRANSITION METAL IMPURITIES IN SEMICONDUCTORS
This book discusses the theory of the electron states of transition metal impurities in semiconductors in connection with the general theory of isoelectronic impurities.
Also included are applications of the theory to the optical, electrical and resonance properties of semiconductors doped by the transition metal impurities.
It describes the theory in the context of the general theory of neutral impurities in semiconductors and demonstrates the capabilities of this description to explain the basic experimental properties of semiconductors doped by transition metal impurities.
www.worldscibooks.com /physics/2470.html   (310 words)

  
 Colors of transition metal ions   (Site not responding. Last check: 2007-10-21)
When you seek the finest references all about colors of transition metal ions, be ready for frustrations and difficulties relevant out the effective information from completely inadequate colors of transition metal ions expertise and direction so it's wise to know how to realize what is delivered.
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www.ion-sales.info /colors_of_transition_metal_ions.htm   (306 words)

  
 Articles - Transition metal
However, many interesting properties of the transition elements as a group are the result of their partly filled subshells from ´´d´´; orbitals, a property which all members of the d-block except zinc, cadmium and mercury share.
As with many properties of transition metals, this is due to ´´d´´; orbital electrons´; ability to delocalise within the metal lattice.
Osmium and ruthenium compounds are commonly isolated in stable 8+ oxidation states, which is among the highest for isolable compounds.
www.sterlingsilvercenter.com /articles/Transition_metal   (1097 words)

  
 GCSE Notes on The Transition Metals Series at Doc Brown's Chemistry Clinic. bttmnwpb wpbchemhelp
The bonding between the atoms in transition metals is very strong (bond notes).
Another consequence of the strong bonding between the atoms in transition metals is that they are tightly held together to give a high density.
Many transition metals are used directly as catalysts in industrial chemical processes and in the anti-pollution catalytic converters in car exhausts.
www.wpbschoolhouse.btinternet.co.uk /page04/4_75trans.htm   (2053 words)

  
 complex ions - colour
The Sc ion doesn't count as a transition metal ion because its 3d level is empty.
When the ligands bond with the transition metal ion, there is repulsion between the electrons in the ligands and the electrons in the d orbitals of the metal ion.
The size of the energy gap between them (shown by the blue arrows on the diagram) varies with the nature of the transition metal ion, its oxidation state (whether it is 3+ or 2+, for example), and the nature of the ligands.
www.chemguide.co.uk /inorganic/complexions/colour.html   (2285 words)

  
 introducing transition metals
This page explains what a transition metal is in terms of its electronic structure, and then goes on to look at the general features of transition metal chemistry.
Transition metals and their compounds are often good catalysts.
Transition metals and their compounds function as catalysts either because of their ability to change oxidation state or, in the case of the metals, to adsorb other substances on to their surface and activate them in the process.
www.chemguide.co.uk /inorganic/transition/features.html   (2458 words)

  
 Uses of the Transition Metals
USES OF The uses of the transition metals are wide and varied.
Scandium forms 25 ppm of the earth's crust (cf the better known transition metals cobalt at 29 ppm and copper at 68 ppm).
Nickel is the seventh most abundant transition metal and 22nd most abundant element at 99 PPM Over a quarter of the world production of Ni comes from the Sudbury Basin in Canada, a giant meteor crater measuring 17 by 37 miles.
www.sky-web.pwp.blueyonder.co.uk /Science/TransMetalUses.htm   (1378 words)

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