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Topic: Covalent

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  Covalent bond - Wikipedia, the free encyclopedia
Covalently bonded hydrogen and carbon in a molecule of methane.
Covalent bonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons between two elements, producing a mutual attraction that holds the resultant molecule together.
However, covalent bonding in metals and, particularly between metals and organic compounds is particularly important, especially in industrial catalysis and process chemistry, where many indispensible reactions depend on covalent bonding with metals.
en.wikipedia.org /wiki/Covalent_bond   (1092 words)

 Covalent bond - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-11-05)
Covalent bonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons between atoms, in order to produce a mutual attraction, which holds the resultant molecule together.
Covalent bonding most frequently occurs between atoms with similar (high) electronegativities, where to completely remove an electron from one atom requires too much energy.
Covalent bonds are more common between non-metals, whereas ionic bonding is more common between a metal atom and a non-metal atom.
www.peekskill.us /project/wikipedia/index.php/Covalent_bond   (978 words)

 Encyclopedia: Covalent bond
Electronegativity is the measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond.
In chemistry, a three-center bond is a type of covalent bond, in which one pair of electrons joins three atoms rather than the usual two.
A coordinate covalent bond (also known as dative covalent bond) is a special type of covalent bond in which the shared electrons come from one of the atoms only.
www.nationmaster.com /encyclopedia/Covalent-bond   (2044 words)

 The Covalent Bond
A single covalent bond is a bond in which two atoms are held together by sharing two electrons.
Covalent bonds form between atoms when ionic or metallic bonding is unlikely because the gain or loss of electrons requires large amounts of energy.
A covalent bond in which electrons are shared unequally is called a polar covalent bond; one atom acquires a partial negative charge (d -) and the other acquires a partial positive charge (d +).
www.cartage.org.lb /en/themes/Sciences/Chemistry/Inorganicchemistry/Informationbonding/CovalentBond/CovalentBond.htm   (727 words)

 Duran: Chapter Eleven Covalent Bonds   (Site not responding. Last check: 2007-11-05)
Covalent bonds result in a net strong attraction between the bonding atoms.
Furthermore, when covalent bonds are formed with multiple atoms around a given atom, a "Network Covalent" structure can form.
As discussed in lecture true nonpolar covalent bonds only form when diatomic molecules are formed from 2 identical atoms; otherwise polar covalent bonds form.
www.chem.ufl.edu /~chm2040/Notes/Chapter_11/covalent.html   (614 words)

 Covalent: Providing Apache Support, Tomcat Support and Axis Support to the Enterprise
Covalent has assembled the deepest talent pool of Apache experts in the industry.
Covalent is now offering to its enterprise customers as an add-on support plan offering Hyperic HQ 2.1, the only downloadable management solution designed specifically for mission-critical open source applications.
Covalent Enterprise Ready Server is the first comprehensive enterprise solution for Apache server management.
www.covalent.net   (281 words)

 Covalent Radius
Across a period, covalent radius decreases because effective nuclear charge increases (due to an increase in no. of protons and little increase in shielding) therefore shells are pulled closer towards the nucleus.
Covalent radius increases down a group due to the constant effective nuclear charge and increase in no. of shells at increasing distances from the nucleus.
Covalent radius is constant across the first row of transition metals because despite an increase in no. of protons across the period, electrons enter the inner 3D subshell, therefore the increase in nuclear charge is shielded so all the transition metals feel the same effective nuclear charge.
www.revision-notes.co.uk /revision/666.html   (175 words)

Covalent compounds are in the form of stable molecules.
Covalent molecules are held together by weak inter molecular force of attraction.
Formation of coordinate covalent bond is the property of atoms that have lone pair of electrons.
www.citycollegiate.com /bondIXe.htm   (177 words)

 Chemical Bonds
Covalent chemical bonds involve the sharing of a pair of valence electrons by two atoms, in contrast to the transfer of electrons in ionic bonds.
Covalent bonds in which the sharing of the electron pair is unequal, with the electrons spending more time around the more nonmetallic atom, are called polar covalent bonds.
When hydrogen atoms are joined in a polar covalent bondwith a small atom of high electronegativity such as O, F or N, the partial positive charge on the hydrogen is highly concentrated because of its small size.
hyperphysics.phy-astr.gsu.edu /hbase/chemical/bond.html   (698 words)

 CNN - Does Covalent have a recipe for open-source success? - December 28, 1999
Thus, when Covalent Technologies appeared in the public-relations bitstream last week with news that it had secured five million dollars in venture capital funding from H&Q Venture Associates, it seemed that this company was following what has become, for some at least, a path to riches.
Covalent is demonstrating how to make money by following the model ESR calls "give away the recipe, open a restaurant." This the very same model that Robert Young followed with Red Hat and Michael Tiemann followed with Cygnus.
Covalent Technologies was founded in 1994, a year before the birth of Apache.
archives.cnn.com /1999/TECH/computing/12/28/covalent.idg   (1311 words)

 JCE 1997 (74) 1494 [Dec] The Mechanism of Covalent Bonding
Covalent bonding is the natural consequence of the electron delocalization that occurs when two or more atoms form a stable molecule by the process of electron sharing.
In an effort to present an easily accessible physical picture, covalent bonding is often described in terms of simple (but incorrect) electrostatic models that effectively ignore the quantum mechanical nature of electrons and the importance of delocalization.
In this paper we reexamine the mechanism of covalent bonding, specifically with a view to its teaching, that starts with quantum theory and the interpretation of its predictions, such as electronic delocalization and the concomitant lowering of the electronic energy as bonding occurs.
jchemed.chem.wisc.edu /Journal/Issues/1997/Dec/abs1494.html   (237 words)

 Covalent Binding of Enzymes   (Site not responding. Last check: 2007-11-05)
Therefore, covalent binding may alter the conformational structure and active center of the enzyme, resulting in major loss of activity and/or changes of the substrate.
Covalent attachment to a support matrix must involve only functional groups of the enzyme that are not essential for catalytic action.
Covalent attachment of the enzyme in the presence of a competitive inhibitor or substrate.
www.rpi.edu /dept/chem-eng/Biotech-Environ/IMMOB/covalent2.htm   (431 words)

 Covalent: Providing Apache Support, Tomcat Support and Axis Support to the Enterprise
Covalent has since assembled the deepest talent pool of Apache experts in the industry and is proud to be one of the most distinguished supporters of the Apache Software Foundation (ASF), the dominant community for useable open source, and the open source community in general.
Covalent has been the trusted source that Fortune 1000 enterprises rely on when migrating to open source and when deploying new open source initiatives.
Covalent now supports many of the world's largest IT operations groups and Web infrastructures-- including more than 50% of the Fortune 500 and more than 70% of the Fortune 100 companies.
www.covalent.net /about   (263 words)

 Bond Lengths and Energies
For example, the covalent radii of H and C are 37 and 77 pm respectively.
For covalent bonds, bond energies and bondlengths depend on many factors: electron afinities, sizes of atoms involved in the bond, differences in their electronegativity, and the overall structure of the molecule.
Covalent bonds such as H-Cl, H-I etc are polar, because the bonding electrons are attracted to the more electronegative atoms, Cl and I in these cases.
www.science.uwaterloo.ca /~cchieh/cact/c120/bondel.html   (854 words)

 Covalent bonds   (Site not responding. Last check: 2007-11-05)
Covalent bonds are forces that hold atoms together.
There is a type of covalent bond called a polar covalent bond.
In Biological systems, polar covalent bonds are important because these kinds of bonds allow the formation of another kind of weak bond called a hydrogen bond.
academic.brooklyn.cuny.edu /biology/bio4fv/page/covalenb.htm   (222 words)

 PRESS RELEASE Covalent Technologies(TM) Releases Enterprise Ready Server(TM) 3.0   (Site not responding. Last check: 2007-11-05)
Covalent ERS 3.0 is available on Solaris, Linux, HPUX, IBM AIX, and Windows and may be purchased as a commercial license or through an annual subscription plan.
Covalent Technologies is the leading provider of products and services for Apache Tomcat and Apache, the world's leading Web server, and the only source for full commercial support for Apache and Tomcat on a global basis.
Covalent has assembled the deepest talent pool of Apache experts in the industry and is proud to be one of the most distinguished supporters and stewards of the Apache Software Foundation (http://www.apache.org) (ASF), the dominant community for useable Open Source, and the Open Source community in general.
www.marketwire.com /mw/release_html_b1?release_id=87307   (1152 words)

 Covalent: Providing Apache Support, Tomcat Support and Axis Support to the Enterprise
Covalent, which was selected as an UPSIDE Hot 100 company in the Internet Infrastructure category, was one of 100 private companies singled out by the editors of UPSIDE and an advisory panel comprised of venture capitalists, financial analysts, and market researchers.
Covalent was founded in 1998 by Randy Terbush, one of the eight developers who created the Apache Web Server.
All Covalent product names are trademarks of Covalent Technologies, Inc. All other company and product names are trademarks or registered trademarks of their respective owners.
www.covalent.net /news/pressreleases.html?pressid=6   (500 words)

 CHEMTUTOR COMPOUNDS   (Site not responding. Last check: 2007-11-05)
A covalent bond is the result of the sharing of a pair of electrons between two atoms.
In saying or writing the name of a binary covalent the FGP of the first element is said, then the name of the first element is said, then the FGP of the second element is said, and the name of the second element is said, usually with the ending “-ide” on it.
Materials of a mildly covalent nature, such as small alcohols and sugars, are soluble in water due to the mostly covalent nature of the bonds in water.
www.chemtutor.com /compoun.htm   (4889 words)

 Chemistry:Covalent Bonding
In covalent bonding, pairs of electrons are shared between the two non-metals.
In a dative covalent bond, both of the shared electrons in the bond have come from one atom.
The dative covalent bond is shown using an arrow, with the arrow pointing to the atom accepting the electrons.
sixthsense.osfc.ac.uk /chemistry/bonding/covalent.asp   (821 words)

 SparkNotes: Organic Covalent Bonding: Covalent Bonds and Lewis Structures
A molecule is a collection of atoms held together by covalent bonds.
The bond order of a covalent interaction between two atoms is the number of electron pairs that are shared between them.
When covalent bonds are formed between atoms of different electronegativities the result is that the shared electrons skew more toward one atom than the other.
www.sparknotes.com /chemistry/organic1/covalentbonding/section1.html   (1262 words)

 The Covalent Group   (Site not responding. Last check: 2007-11-05)
Covalent Group Inc. (Nasdaq: CVGR) is an international contract research and health management organization providing a full spectrum of services to the pharmaceutical, biotechnology and medical device industries.
Covalent provides its clients with a complete clinical research turn key solution through a combination of its unique understanding of clinical trial design and the regulatory approval process, proprietary technology, precise data management, and world class expertise.
Covalent’s management team is led by CEO, Dr. Ken Borow, a Harvard trained physician and world-renowned cardiologist, and one of the world’s leading authorities on the technology and applications of non-invasive imaging (e.g., ultrasound [echo], computed tomography [CT]).
www.murdockcapital.com /covalent.htm   (689 words)

 BBC - GCSE Bitesize - Chemistry | Classifying Materials | Representing covalent bonds
Covalent bonds can be represented in several different ways.
A double covalent bond is shown by a double line, and a triple bond by a triple line.
A double bond is a covalent bond resulting from the sharing of four electrons (two pairs) between two atoms.
www.bbc.co.uk /schools/gcsebitesize/chemistry/classifyingmaterials/covalent_bondingrev3.shtml   (437 words)

 Covalent bonding   (Site not responding. Last check: 2007-11-05)
This current occurs when a covalent bond is broken and a vacancy is left in the atom by the missing valence electron.
This vacancy is commonly referred to as a "hole." The hole is considered to have a positive charge because its atom is deficient by one electron, which causes the protons to outnumber the electrons.
Since hole flow results from the breaking of covalent bonds, which are at the valence band level, the electrons associated with this type of conduction contain only valence band energy and must remain in the valence band.
www.tpub.com /neets/book7/24d.htm   (1054 words)

 MIT Biology Hypertextbook: Chemistry Review   (Site not responding. Last check: 2007-11-05)
Covalent Bonds are the strongest chemical bonds, and are formed by the sharing of a pair of electrons.
The energy of a typical single covalent bond is ~80 kilocalories per mole (kcal/mol).
A hydrogen atom covalently attached to a very electronegative atom (N, O, or P) shares its partial positive charge with a second electronegative atom (N, O, or P).
web.mit.edu /esgbio/www/chem/review.html   (838 words)

 : Covalent Bonding, review at WorldSSP.net   (Site not responding. Last check: 2007-11-05)
COVALENT BONDING - SINGLE BONDS This page explains what covalent bonding is. It starts with a simple picture of the single covalent bond, and then modifies it slightly for A'level purposes.
Covalent Bonds Covalent bonds are forces that hold atoms together.
SCH4U Coordinate Covalent Bonding Sometimes one atom supplies both of the electrons that are shared in a covalent bond.
www.worldssp.net /webinfo_m.asp?proid=12387   (499 words)

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