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Topic: Bond length

  Bond length - Wikipedia, the free encyclopedia
bond length or bond distance in molecular geometry is the distance between two bonded atoms in a molecule.
Bond length is also directly related to bond strength and the bond dissociation energy as a stronger bond is also a shorter bond.
In a bond between two identical atoms half the bond distance is equal to the covalent radius.
en.wikipedia.org /wiki/Bond_length   (259 words)

 Hydrogen bond - Wikipedia, the free encyclopedia
Generally, the hydrogen bond is characterized by a proton acceptor that is a lone pair of electrons in nonmetallic atoms (most notably in the nitrogen, and chalcogen groups).
Neutron diffraction has shown that the molecular geometry of these complexes are similar to hydrogen bonds, in that the bond length is very adaptable to the metal complex/hydrogen donor system.
The hydrogen bond remains a fairly mysterious object in the theoretical study of quantum chemistry and physics.
en.wikipedia.org /wiki/Hydrogen_bond   (1172 words)

 Hydrogen bonds in water
one of the hydrogen bonds in ice-four (143°).
Cooperative hydrogen bonding increases the O-H bond length whilst causing a 20-fold greater reduction in the H····O and O····O distances [436].
An interesting way of describing the cooperative/anticooperative nature of the water dimer hydrogen bond is to use the nomenclature d'a'DAd''a'' where DA represents the donor-acceptor nature of the hydrogen bond, the d'a' represents the remaining donor-acceptor status of the donating water molecule and d''a'' represents the remaining donor-acceptor status of the accepting water molecule [852].
www.lsbu.ac.uk /water/hbond.html   (3675 words)

 Bond Lengths and Energies
Bond energy is a measure of the strength of a chemical bond.
Bonds between the same type of atom are covalent bonds, and bonds between atoms when their electronegativity differs by a little (say 0.7) are also predominant covalent in character.
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.
www.science.uwaterloo.ca /~cchieh/cact/c120/bondel.html   (854 words)

 ChemViz Hydrogen Bonding Lab   (Site not responding. Last check: 2007-10-04)
In the special case when the H pole of one molecule is bonded to either the F, O, or N pole of a second molecule, the interaction is known as a hydrogen bond.
An optional method for more accurately determining the bond length between H and F is to run a ChemViz job to optimize the geometry of the H-F molecule based on the approximate bond length determined in Procedure I. Select one H atom and one F atom from the periodic table.
Set the position of the H at "-" one-half the value of the approximate bond length in Ångstroms, and the position of the F atom at "+" one-half the value of the approximate bond length in Ångstroms.
chemviz.ncsa.uiuc.edu /content/lab-s-hbond.html   (1726 words)

 Bond and Development   (Site not responding. Last check: 2007-10-04)
Four different surface preparations of the concrete were studied: bonding to the "as cast specimen", grinding the concrete surface smooth, mechanically abrading the concrete surface, and acid etching or priming the concrete surface.
The length of the bond was left constant for the preliminary bond tests, then varied between 2 in., 4 in., 6 in., and 8 in., in order to determine the force transfer of the applied load into the concrete.
Maximum effective bond length is determined, and recommendations are made as to the surface preparation techniques, adhesive type, and bond length needed to achieve an acceptable bond.
www.ce.udel.edu /faculty/chajes/bond.html   (316 words)

 Chemical Bonding
Bond Length is the average distance between the centers of two bonded atoms.
The term Bond Length specifically refers to the average positions of the two atoms during the harmonic vibrations that they undergo.
Bond Order is the term used to distinguish between the number of bonds that exist between two atoms.
www.bcpl.net /~kdrews/bonding/bonding.html   (798 words)

 Vibration-Rotation Spectrum of HCl
A bond length for the HCl molecule can be calculated from the HCl spectrum by assuming that it is a rigid rotor and solving the Schrodinger equation for that rotor.
Assuming that the bond length is the same for the ground and first excited states, the difference between the j=1,v=0->j=0,v=1 transition and the j=0,v=0->j=1,v=1 transition frequencies can be used to estimate the bond length.
The separation between the two illustrated vibration-rotation transitions is assumed to be twice the rotational energy change from j=0 to j=1.
hyperphysics.phy-astr.gsu.edu /hbase/molecule/vibrot.html   (482 words)

 Bond Energy   (Site not responding. Last check: 2007-10-04)
The optimum bond length between a pair of atoms is the distance at which there is a minimum energy value.
The bond is most stable when the value displayed in red (labeled "bond energy") is at its lowest value (most negative).
Find the bond length that results in the most stable bond between the two atoms in the Group V, VI, and VII homonuclear diatomic molecules in Period 2.
www.bu.edu /smec/qsad/curriculum/text_modules/Bond_Energy.htm   (436 words)

 EJGE Paper
Using the method of finite elements, it is possible to analyse the activation of bond stresses under various values of external loads, resulting in the force-displacement curves at the proximal end of the anchor, and the displacement analysis along the anchor length.
The proposed process of calculating the force distribution, displacement, and bond stresses along the fixed anchor length will be presented, which can fill the void between the rough calculations, based on crude empirical knowledge, and sophisticated analyses, for which one must have the appropriate exactness of input parameters.
Maximum force and displacement are activated at the proximal end of anchor, and gradually decrease toward the distal end because of bond stresses having an effect on the contact of injection mass with the surrounding ground.
www.ejge.com /2003/Ppr0303/Ppr0303.htm   (2606 words)

 Ch9_Bonds.cw.html   (Site not responding. Last check: 2007-10-04)
Bonds are formed by sharing electrons between neighboring nuclei; Recall that negative charges are attracted to positive charges.
For two atoms bonded to each other, a difference in the electronegativity (page 327) of the two atoms causes an unequal sharing of the electrons in the bonds between the two atoms.
The size of the atomic valence orbitals: Bond lengths increase as the atomic valence orbitals become larger.
www.chem.lsu.edu /htdocs/people/lgbutler/1202_Fall96/WebInit/Ch9_Bonds.html   (1033 words)

 VSEPR and bond angles
Note that the bond lengths increase in a way we can understand easily: H is smaller than F, which is smaller than Cl.
Moreover, the experimental bond lengths to the O atom are quite close to our expectations from the original three molecular structures.
case: sometimes the ligands are so big that, at their ideal bond length, they have to form a bond angle larger than ideal because the ligand repulsion is greater than the lone pair–bonding pair repulsion and ligand repulsion determines the final geometry.
www.dartmouth.edu /~genchem/0102/spring/6winn/VSEPR2.html   (617 words)

 The Actinide Research Quarterly: 1st Quarter 2004
In the course of our studies of structure and bonding in actinide complexes in high-oxidation states, we have examined a variety of axial dioxo systems in which the linear O=An=O moiety is both highly sensitive to the electronic configuration of the complex and also yields a characteristic Raman band, identified as the symmetric stretch n1.
His "rule," which relates a change in stretching frequency with a change in bond lengths, was the result of his extensive study the force constant and internuclear distance in a large number of diatomic molecules.
Badger-type relations provide a link between bond strength and bond length, which in turn, provides important constraints to check the theoretical calculations (with their associated approximation methods) performed to inform us of the orbitals used in constructing the molecule.
www.lanl.gov /source/orgs/nmt/nmtdo/AQarchive/04spring/correlation.html   (1276 words)

 The Fluoride Ion and The Carbanions
Using bond length as a proxy for hardness, the behaviour of the anomalous fluoride ion can be explained.
Thus, organic chemistry with its special emphasis on the C–C bond has the fluoride ion, F–;, harder than the carbanion at delta+ carbon centres whereas the chloride, bromide and iodide are softer.
The "to H" bond length of the conjugate Brønsted acid correlates with intrinsic nucleophilicity, a measure of reactivity towards delta+ carbon centres.
www.meta-synthesis.com /webbook/10_fluoride/fluoride.html   (1340 words)

 [No title]
The relationship between bond length (R) and bond valence (s) is: s = exp((Ro - R)/B) where Ro and B are bond valence parameters that depend on the two atoms forming the bond.
alence, except the valence is the input and the length is the output.
The bond type is selected as for the valence calculation described above, but all the bond lengths in the environment of the first-entered atom are typed in at the 'length' prompt section, each separated by
www.ccp14.ac.uk /ccp/web-mirrors/i_d_brown/valence.txt   (1829 words)

 MCCCS Towhee (towhee_ff)   (Site not responding. Last check: 2007-10-04)
The bond pattern is used with configurational-bias moves that utilize a non-uniform generation of the bond angles and dihedrals.
where the two bond terms involve the bond lengths in the angle, and the appropriate vibcoeffs for that type of bond.
The bond and angle terms that appear in the cross terms use the appropriate vibcoeff and bencoeff parameters for the bond or angle in question.
www.cs.sandia.gov /projects/towhee/towhee_ff.html   (3018 words)

 Chemistry: WebElements Periodic Table : Periodic properties : Bond length in element: Definition
This length refers to the internuclear separation between the atoms in the element.
Lengths do depend upon the allotrope, or form of the element, to some extent.
Thus, the C-C length in graphite is 142.6 pm whereas the C-C length in diamond is 154.1 pm.
www.webelements.com /webelements/properties/text/definitions/bond-length-elem.html   (229 words)

 exercise 2: C-H Bond length as a function of "n" in "spn"   (Site not responding. Last check: 2007-10-04)
The character of a sigma-type bond depends on the nature of its building blocks - the atomic, or group orbitals which overlap to create the bond.
The bond length can serve as an excellent probe to monitor the sigma bond character: In general - the more "s"-type orbitals it contains, the shorter it is expected to be.
In this exercise, you will compare the C-H bond length in a series of hydrocarbons with different "hybridization" of the the group orbitals participating in the sigma bonds.
www.biu.ac.il /CH/CC_Exercises/ex2.html   (219 words)

 Curious or dubious: The story of a hydrocarbon with an exceptionally short C=C bond length   (Site not responding. Last check: 2007-10-04)
While all the geometrical parameters were typical of the subunits present in the molecule, the double bond length in the ring was found to be exceptionally short.
The key discrepancies between the experimental and calculated bond lengths are shown in the structure drawing.
The central bond length changes from 1.506 Å to the almost normal 1.529 Å as the crystal is cooled from 240 to 100 K. In the related dimethyl derivative 3c, the distance is nearly normal in the entire temperature range.
www.ias.ac.in /currsci/jun25/articles6.htm   (1820 words)

 WLC model
With the assumption that L is the average bond length the average square chain vector simplifies to Equation 2, where the brackets denote the statistical average over all conformations.
The freely jointed chain is defined as having a Kuhn length equal to the bond length, Equation 6.
The characteristic length describing the force of extension in the WLC model in is the persistence length (q).
www.pitt.edu /AFShome/g/i/gilbertw/public/html/jason/wlc.html   (750 words)

 [No title]   (Site not responding. Last check: 2007-10-04)
We will examine the two factors which are required for a bond to be polar: a difference in electronegativity of the atoms in the bond and the effect of bond length.
That is determined by the atomic masses of the bonded atoms, and the stiffness of the bond.
When it is complete, record the bond length and dipole moment in the Part C Data Table.
web.chem.ucla.edu /~harding/132BH_4.html   (1184 words)

 Non Classical Effects in Main Group Elements   (Site not responding. Last check: 2007-10-04)
The "double" bond in 2 is nearly twice as strong as the "single" bond in 1.
The nomenclature used for multiply bonded Group 14 compounds, especially those of silicon, is a little confusing and not consistent in all literature.
It would therefore be expected that bending would be resisted where the M-M bonding is strong: when the M-M bond is short as it is for M = C. For the heavier elements, the M-M bonding is weaker so that bending is resisted to a lesser extent.
www.hull.ac.uk /php/chsajb/non-classical/handout_1.html   (3017 words)

length (how do you know?) bond vectors are shown along with the (x,y) coordinates of their tips.
bond vectors is again attached to a common origin (the C atom in this case).
H atom #1) and bond vector #2 (i.e., the vector attaching H atom #2).
dept.physics.upenn.edu /courses/gladney/mathphys/java/sect1/chdotans1.html   (1384 words)

 General Chemistry Online: FAQ: Chemical bonds: How does MO theory explain bond length trends for O_2_ and its ions?
Bond strength depends on how stretchy or stiff the bonds are (with stiffer bonds being stronger).
Since an increase in bond order leads to stronger bonds, there is an expectation that higher bond order means shorter bonds.
In the table below, the bond orders are predicted from electron configurations by subtracting the number of electrons in bonding orbitals from the number of electrons in antibonding (*) orbitals, and dividing by two.
antoine.frostburg.edu /chem/senese/101/bonds/faq/oxygen-mo-and-bond-length.shtml   (145 words)

 Chapter 8 - Bond Length, Strength & Order
In a molecule as you increase the number of electrons shared between two atoms, you increase the bond order, increase the strength of the bond, and decrease the distance between nuclei.
We experimentally measure bond lengths using x-ray and neutron diffraction, which was mentioned briefly in chapter 6.
Then remember to multiply the number of bonds in each molecule by the coefficient in front of the molecule.
www.chemistry.ohio-state.edu /~woodward/ch121/ch8_bondorder.htm   (411 words)

 Bond Length of CFRP Composites Attached to Precast Concrete Walls   (Site not responding. Last check: 2007-10-04)
A panel assembly made up of three precast concrete walls was loaded in the in-plane direction using a cyclic quasi-static load, which was transferred to the wall interface as a shear force.
An expression, which compares well with the experimental findings, is presented for the effective bond length of carbon fiber composite sheets.
The effective bond length of the connection depends on the peel-off shear strength of the concrete, the maximum tensile strain in the composite, modulus of elasticity, and thickness of the composite plate.
www.pubs.asce.org /WWWdisplay.cgi?9904333   (179 words)

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