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Topic: Dipole moment


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In the News (Sun 21 Jul 19)

  
  Torque on an Electric Dipole
is the magnitude of the electric dipole moment.
The tendency of the electric field to align the dipole moment with itself is confirmed by the potential energy formula.
The potential energy is lowest when the dipole moment is aligned with the field and highest when the two are anti-aligned.
www.physics.nmt.edu /~raymond/classes/ph13xbook/node155.html   (316 words)

  
 D - Glossary of chemical terms
Dipole moments are often stated in debyes; The SI unit is the coulomb metre.
In a diatomic molecule, such as HCl, the dipole moment is a measure of the polar nature of the bond; i.e.
In a polyatomic molecule, the dipole moment is the vector sum of the dipole moments of the individual bonds.
www.ktf-split.hr /periodni/en/abc/d.html   (830 words)

  
  Ionic and Covalent Binding - Dipole Moments and Polar Bonds
To illustrate the definition of the dipole moment we shall determine this property for the LiF molecule assuming that one electron is transferred from Li to F and that the charge distributions of the resulting ions are spherical.
The dipole moment is defined as the product of the total amount of positive or negative charge and the distance between their centroids The centroids of the positive and negative charges in a molecule are determined in a manner similar to that used to determine the centre of mass of a system.
Thus, not surprisingly, the dipole moment in this case is numerically equal to one excess positive charge at the Li nucleus and one excess negative charge at the F nucleus, or one pair of opposite charges separated by the bond length.
www.chemistry.mcmaster.ca /esam/Chapter_7/section_3.html   (2891 words)

  
  Anisotropic electric properties of purple membrane and their change during the photoreaction cycle. -- Kimura et al. ...
size: the permanent dipole moment ranged from 500 kD to 10 MD and was proportional to the square of the diameter of the membrane.
Because the permanent dipole moment was proportional to the
permanent dipole moment decreased from 98 to 63 D/bacteriorhodopsin.
www.biophysj.org /cgi/content/abstract/45/3/615   (261 words)

  
 Dipole Summary
The dipole moment is equal to the magnitude of the equal and opposite charges multiplied by the distance between the centers of the charge distributions.
The dipole moments of the hydrogen-halide sequence HF, HCl, HBr, and HI are 1.98, 1.03, 0.79, and 0.38 respectively.
For magnetic dipoles, the dipole moment points from the magnetic south to the magnetic north pole — confusingly, the "north" and "south" convention for magnetic dipoles is the opposite of that used to describe the Earth's geographic and magnetic poles, so that the Earth's geomagnetic north pole is the south pole of its dipole moment.
www.bookrags.com /Dipole   (2186 words)

  
 Molecular Dipole Moments
This is called polarization and the magnitude of the dipole moment induced is a measure of the polarizability of the molecular species.
The measured magnitude of this dipole moment is
The dipole moment of water provides a "handle" for interaction with microwave electric fields in a microwave oven.
hyperphysics.phy-astr.gsu.edu /hbase/electric/diph2o.html   (386 words)

  
 Dipole
A dipole is a pair of electric charges or magnetic poles of equal magnitude but opposite polarity, separated by some (usually small) distance.
Dipoles can be characterized by their dipole moment, a vector quantity with a magnitude equal to the product of the charge or magnetic strength of one of the poles and the distance separating the two poles.
The direction of the dipole moment corresponds to the direction from the negative to the positive charge or from the south to the north pole.
www.knowledgefun.com /book/d/di/dipole.html   (506 words)

  
 Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal   (Site not responding. Last check: )
For the simple electric dipole given above, the electric dipole moment would point from the negative charge towards the positive charge, and have a magnitude equal to the strength of each charge times the separation between the charges.
For the current loop, the magnetic dipole moment would point through the loop (according to the right hand rule), with a magnitude equal to the current in the loop times the area of the loop.
The permanent dipole moment of an atom in a non-degenerate state (see degenerate energy level) is given as the expectation (average) value of the dipole operator,
www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=magnetic_dipole   (1705 words)

  
 Bond Dipole Moments
The distance of charge separation depends primarily on the length of the bond and this bond length is affected strongly by the atomic radii of the bonding partners.
In the calculation of the dipole moment, the charge separation acts as a scaling factor for the electronegativity differences of the bonding partners.
The bond dipole moments given below are averages calculated using molecules of known structure and for which the molecular dipole moment has been measured.
www.towson.edu /~debye/chem110/handouts/110_bond_dipole_moments.html   (234 words)

  
 Permanent Dipole Moment
The permanent dipole moment as the name suggests differs from induced polarization in that it is a permanent separation.
The permanent dipole moment is defined as the vector sum of the individual charge moments within the molecule.
Therefore the lower the dipole moment the greater the insecticidal action.
www.utmem.edu /physpharm/.007.html   (129 words)

  
 Magnetic moment Summary
In physics, the magnetic moment or magnetic dipole moment is a measure of the strength of a magnetic source.
The moment is negative, indicating it is diamagnetic, and equal to the energy of rotation divided by the magnetic field.
The magnetic moment of an object is a vector relating the aligning torque in a magnetic field experienced by the object to the field vector itself.
www.bookrags.com /Magnetic_moment   (978 words)

  
 Understanding Prion Structure
The pattern is out-of-sequence anti-parallel, ie, there are constructive dipole-dipole interactions between pairs of helices and also with the bipolar dipole, as the dipoles are oriented nose to tail and a few angstroms apart in the 3D picture.
If prion protein forms a oligomer, we might expect the dipole moment of each subunit to be antiparallel, causing partial cancellation of the net dipole moment, as Takashima observed for tetramers such as normal hemoglobin (Biophys J 64: 1550 1993).
The overall dipole moment of red algal flavodoxin is said to be important in its interactions with other proteins (J Biol Chem 265: 15804 1990).
www.mad-cow.org /prion_dipoles.html   (1026 words)

  
 A Permanent Dipole Moment in Nanocrystals: Rethinking Spherical Assumptions   (Site not responding. Last check: )
The dipole moment is calculated simply as the product of the magnitude of the charge and the distance between them.
The dipole moment of all of the nanocrystals is measured as the magnitude of the change of voltage.
The second method of measuring dipole moment involves shining visible light on the nanocrystals and inducing excitation.
mrsec.uchicago.edu /Nuggets/Dipole   (1090 words)

  
 Protein Dipole Moments Server
The quadrapole moments are now calculated according to the formula, for each atom i, Qx(i) = 0.5q(i)*(3x(i)**2 - r(i)**2), and similar for Qy and Qz, where q(i) is the atom's partial charge, x(i) is its X-coordinate and r(i) is its distance from the center-of-mass origin.
In the pictures, the dipole vector is represented by a red line, and the truncated mass moment vector is a short line, half red and half fl.
The origin of the red dipole line corresponds with the net negative charge, and the far end with the net positive charge of the dipole moment.
bioportal.weizmann.ac.il /dipol   (928 words)

  
 MAGNETIC MATERIALS
The total magnetic moment of an atom is equal to the vector sum of the orbital magnetic moments and the intrinsic magnetic moments of all its electrons.
In a diamagnetic material the dipole moments of the atoms do not align themselves with the magnetic field, but their strength is changed by the external field.
The change in the dipole moment as function of the applied magnetic field can be estimated using a simple classical model in which the electron moves in a circular orbit around the nucleus (see Figure 2).
teacher.nsrl.rochester.edu /phy122/LectureNotes/Chapter33/chapter33.html   (1806 words)

  
 Compton Group Areas of Research
These molecules include those with low dipole moments of about 2.8 D such as acetone and cyclohexanone to those with large dipole moments of 4 and 5 Debye such as acetonitrile.
Molecules with low dipole moments accept electrons that have been excited to very high Rydberg states (such as n=50) whereas molecules with high dipole moments accept electrons that have been excited to very low Rydberg states (such as n=10).
Since dipole moments and other molecular properties aren’t known for some of the molecules we study they need to be calculated at a high degree of accuracy.
web.utk.edu /~rcompton/dipole.htm   (748 words)

  
 EDM in Storage Rings Collaboration Home Page
The electric dipole moments (EDM) of fundamental particles are excellent probes of physics beyond the standard model (SM), e.g.
This method is based on the highly innovative approach of canceling the g-2 precession in the horizontal plane by using a radial electric field.
We are proposing a new method to carry out a dedicated search for a permanent electric dipole moment (EDM) of the muon with a sensitivity at a level of 10^{-24} e cm.
www.bnl.gov /edm   (938 words)

  
 The Reference Frame: Electric dipole moments
A dipole moment is a vector, and by rotational symmetry, the only direction that the dipole could take is the direction of the spin.
No dipole moments of the elementary particles have been found so far which puts strong constraints on the parameters of new theories such as MSSM (minimal supersymmetric Standard Model) as well as baryogenesis (but no constraints on leptogenesis).
Quantoken, for an electron, 99.884% of the magnetic dipole moment comes from the core and only 0.116% comes from the polarised vacuum which couples a virtual fermion to the core, increasing the total magnetism as Schwinger and Feynman found.
motls.blogspot.com /2005/12/electric-dipole-moments.html   (1333 words)

  
 Molecules test electron dipole (February 2002) - News - PhysicsWeb
The electron’s electric dipole moment is a measure of the average distance of charge from the electron’s centre of mass.
The dipole moment is parallel to the direction in which the electron spins because any other component of charge distribution would be averaged to zero by the motion of the spin.
The virtue of measuring the dipole moment of electrons in molecules rather than heavy atoms – which are currently used – is that they can generate far higher electric fields and therefore mask the unwanted magnetic effects.
physicsweb.org /article/news/6/2/13   (599 words)

  
 The permanent and induced magnetic dipole moment of the moon
The induced moment opposes the external field, implying the existence of a substantial lunar ionosphere with a permeability between 0.63 and 0.85.
We note that if the moon has a significantly large induced dipole moment, then the measurement of the permanent dipole moment may be affected, unless care is taken to give equal weight to data from both lobes of the geomagnetic tail in which the external field is oppositely directed.
The technique for the measurement of the induced dipole moment is identical to that for the permanent moment with two modifications.
www-spc.igpp.ucla.edu /personnel/russell/papers/permanent(7)   (4528 words)

  
 Electric dipole moment
How much charge is actually transferred can be quantified by studying the electric dipole moment of the bond, which is a quantity that can be measured experimentally.
Hence, the magnitude of the dipole moment is
The units of the dipole moment are Coulomb
www.nyu.edu /classes/tuckerman/honors.chem/lectures/lecture_7/node5.html   (225 words)

  
 dipole moment definition - Dictionary - MSN Encarta
dipole moment definition - Dictionary - MSN Encarta
Search for "dipole moment" in all of MSN Encarta
result of magnetic dipole: the product of two equal and opposite magnetic poles or electric charges that are separated by a short distance
encarta.msn.com /dictionary_1861689082/dipole_moment.html   (113 words)

  
 Lab 4
The molecular properties of interest are the energy (wavelength), intensity of the transition (oscillator strength), and the change in dipole moment upon excitation.
A log file was used to determine the wavelength, oscillator strength, and State Dipole moments for several molecules with electron donating and accepting groups.
The angle and dipole moment were measured for each molecule; the PM3 calculated dipole moment for each molecule was compared to the dipole moment calculated using the vector addition method.
ed.augie.edu /~djpaulso/indexBB6.html   (666 words)

  
 Use of Point Groups   (Site not responding. Last check: )
A molecule will have a dipole moment (that is, it will be polar) if the bond dipole moments do not cancel each other out.
Actually, it is the change in the molecular dipole moment when the atoms vibrate that determines whether the vibration is or is not IR active.
In this mode the dipole moment for the molecule does not change in direction, but it does change in magnitude.
www.reciprocalnet.org /edumodules/symmetry/pointgroups/use.html   (919 words)

  
 Intermolecular Forces   (Site not responding. Last check: )
The difference between the electronegativities of the atoms in these molecules is large enough that the electrons aren't shared equally, and yet small enough that the electrons aren't drawn exclusively to one of the atoms to form positive and negative ions.
HCl molecules, for example, have a dipole moment because the hydrogen atom has a slight positive charge and the chlorine atom has a slight negative charge.
By distorting the distribution of electrons around the argon atom, the polar HCl molecule induces a small dipole moment on this atom, which creates a weak dipole-induced dipole force of attraction between the HCl molecule and the Ar atom.
chemed.chem.purdue.edu /genchem/topicreview/bp/intermol/intermol.html   (1020 words)

  
 Electric Dipole
The electric dipole moment for a pair of opposite charges of magnitude q is defined as the magnitude of the charge times the distance between them and the defined direction is toward the positive charge.
It is a useful concept in atoms and molecules where the effects of charge separation are measurable, but the distances between the charges are too small to be easily measurable.
Applications involve the electric field of a dipole and the energy of a dipole when placed in an electric field.
hyperphysics.phy-astr.gsu.edu /hbase/electric/dipole.html   (143 words)

  
 Ch. 5
Induced dipole interactions are also termed dispersion interactions, and they result in the condensation of noble gases such as Ar or Ne.
In small atoms, the electrons are held tightly by the nucleus and are not as readily polarized (distorted) as in larger atoms with electrons further from the nucleus.
Larger molecules, however, have dipole moments that are the vector sum (both the magnitude and direction of the dipole are important in the summation) of bond dipoles.
darkwing.uoregon.edu /~ch225/ch225_ch_5.htm   (1696 words)

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