
	Where results make sense

Topic: London forces

Related Topics

Van der Waals force

Intermolecular force

Instantaneous dipole attraction

London (disambiguation)

Van der Waals Bonding

Johannes Diderik van der Waals

Fritz London

Dipole

Chemical bond

Electron density

Hydride

Electron configuration

Sonoluminescence

Linus Pauling

Helium

	London forces
		Van der Waals forces are responsible for certain cases of pressure broadening (van der Waals broadening) of spectral lines and the formation of van der Waals molecules.
		London dispersion forces, named after the German-American physicist Fritz London, are weak intermolecular forces that arise from the attractive force between transient dipoles (or better multipoles) in molecules without permanent multipole moments.
		London forces can be exhibited by nonpolar molecules because electron density moves about a molecule probabilistically, see quantum mechanical theory of dispersion forces.
	www.algebra.com /algebra/about/history/London-forces.wikipedia (1030 words)

	Kids.Net.Au - Encyclopedia > London forces
		London forces, named after the German physicist Fritz London[?], are weak intermolecular forces that arise from the attractive force between transient dipoles in otherwise nonpolar molecules.
		London forces are much weaker than other intermolecular forces such as ionic interactions, hydrogen bonding, or dipole-dipole interactions.
		Without London forces, there would be no attractive force between these molecules and they could not then be obtained in a liquid form.
	www.kids.net.au /encyclopedia-wiki/lo/London_forces (286 words)

	Van der Waals force - Wikipedia, the free encyclopedia
		Forces that deal with fixed or angle averaged dipoles (Keesom forces) and free or rotation dipoles (Debye forces) as well as shifts in electron cloud distribution (London Forces) are named after the Dutch chemist Johannes Diderik van der Waals who first documented these interactions.
		London forces, named after the German physicist Fritz London, are weak intermolecular forces that arise from the attractive force between transient dipoles (or better multipoles) in molecules without permanent multipole moments.
		The London-Van der Waals force is related to the Casimir effect for dielectric media, the former the microscopic description of the latter bulk property.
	en.wikipedia.org /wiki/Van_der_Waals_force (764 words)

	Chemistry : Chapter 9 : Identifying Intermolecular Forces (Site not responding. Last check: 2007-10-29)
		Nonpolar covalent molecules have London or dispersion forces.
		The forces will be stronger for CaS, since it is made from ions with a charge of 2, whereas KBr is made from ions with a charge of 1.
		The molar mass of bromine is 159.8 g/mol and that for carbon tetrachloride is 153.82 g/mol.
	www.wwnorton.com /chemistry/concepts/chapter9/ch9_1.htm (2326 words)

	Van der Waals force -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-29)
		The Van der Waals force is the force to which the (Any of various small chiefly tropical and usually nocturnal insectivorous terrestrial lizards typically with immovable eyelids; completely harmless) gecko's unique ability to cling to smooth surfaces is attributed.
		London forces are much weaker than other (Click link for more info and facts about intermolecular force) intermolecular forces such as ionic interactions, hydrogen bonding, or permanent dipole-dipole interactions.
		Without London forces, there would be no attractive force between these ((physics and chemistry) the simplest structural unit of an element or compound) molecules and they could not then be obtained in a liquid form.
	www.absoluteastronomy.com /encyclopedia/v/va/van_der_waals_force.htm (737 words)

	Feature Article (Site not responding. Last check: 2007-10-29)
		London and Hamaker’s work on the point to point dispersion interaction and Lifshitz’s development of the continuum theory of dispersion are the foundations of our understanding of dispersion forces.
		Dispersion forces are present for all materials and are intrinsically related to the optical properties and the underlying interband electronic structure of materials.
		London dispersion forces are important in both adhesion and in sintering where the detailed shape at the crack tip and at the sintering neck can be controlled by the dispersion forces.
	www.lrsm.upenn.edu /~frenchrh/feature_article.htm (533 words)

	Quantum Consciousness
		London forces are weak instantaneous couplings between pairs of electron induced dipoles (e.g.
		London forces ensue from the fact that atoms and molecules which are electrically neutral and spherically symmetrical nevertheless have instantaneous electric dipoles due to asymmetry in their electron distribution.
		It is generally recognized that anesthetics bind in hydrophobic pockets of critical brain proteins by attractive van der Waals London forces (the same type of endogenous interactions occurring between non-polar amino acid groups in the absence of anesthet ics).
	www.quantumconsciousness.org /penrose-hameroff/anesthesiahydrophobic.html (3527 words)

	General Chemistry Online: FAQ: Liquids: What are van der Waals forces?
		Intermolecular forces are feeble; but without them, life as we know it would be impossible.
		Transitory forces are sometimes called "London forces" in honor of their discoverer.
		However, they are usually weaker than the permanent forces that they are usually only invoked to explain intermolecular forces between nonpolar molecules or noble gas atoms.
	antoine.frostburg.edu /chem/senese/101/liquids/faq/h-bonding-vs-london-forces.shtml (836 words)

	Chemical Bonding Topic Overview
		Van der Waals forces are commonly classified as either London forces (between molecules of hydrogen and carbon dioxide for example) or dipole-dipole interactions (between molecules of hydrogen chloride and chloroform for example).
		London forces, the weakest of these forces, are caused by momentary fluctuations of electron distribution symmetry in the atoms.
		Although London forces are the weakest of the van der Waals forces, they may be considered the most important.
	www.okstate.edu /jgelder/bondpage3.html (659 words)

	Molecular Attractions: London Dispersion Forces
		There are several important forces that govern the interactions of molecules; it is the nature of these forces that directly determines the melting points, boiling points, and solubility properties of a particular compound.
		The most important forces found in organic molecules are London dispersion forces, dipole-dipole interactions, and hydrogen bonding.
		These forces are very weak; however, the sum of many of these small forces can lead to a very significant net force.
	www.chemhelper.com /molatt.html (183 words)

	Learn more about Chemical bond in the online encyclopedia. (Site not responding. Last check: 2007-10-29)
		In chemistry and allied sciences, a chemical bond is the force which holds atoms together in molecules or crystals.
		The types of bonding are differentiated by the extent to which electron density is localized or delocalized among the atoms of the substance.
		In contrast, the electron density distributions within covalent bonds are not so readily assigned to individual atoms, but are instead delocalized across the molecule in structures sometimes described as molecular orbitals, which may have more directed, anisotropic properties.
	www.onlineencyclopedia.org /c/ch/chemical_bond.html (407 words)

	COTW10
		Remember that the weak forces are the cause for the gaseous state, not the effect of a substance being a gas.
		Unlike water, however, the attractive forces between the nonpolar CO molecules in dry ice are weaker London forces.
		Stronger forces are correlated with a larger enthalpy of vaporization (and a lower vapor pressure), while weaker intermolecular forces are associated with a smaller enthalpy of vaporization (and a higher vapor pressure).
	www2.yk.psu.edu /~jhb3/cotw10.htm (2750 words)

	Supplemental Topics
		A clear conclusion to be drawn from this fact is that intermolecular attractive forces vary considerably, and that the boiling point of a compound is a measure of the strength of these forces.
		Thus, in order to break the intermolecular attractions that hold the molecules of a compound in the condensed liquid state, it is necessary to increase their kinetic energy by raising the sample temperature to the characteristic boiling point of the compound.
		The attractive forces that exist between molecules are responsible for many of the bulk physical properties exhibited by substances.
	www.cem.msu.edu /~reusch/VirtualText/suppmnt1.htm (3808 words)

	London Forces (Site not responding. Last check: 2007-10-29)
		The additional attraction is the result of London forces, which contribute to the attractions between polar molecules as well as nonpolar ones.
		Combined, these forces are strong enough at 84.9 C to cause the HCl to condense to a liquid.
		The increased attractions between polar molecules that come from the higher charges that arise due to instantaneous increases in dipoles and induced increases in dipoles are London forces.
	www.mpcfaculty.net /mark_bishop/London_polar_molecules.htm (441 words)

	Katrina Forces London to Examine Defense (Site not responding. Last check: 2007-10-29)
		London, which sits about 3 feet above sea level, was once extremely vulnerable to surging North Sea tides that would cause the river to suddenly rise.
		London was mostly spared but the damage, in today's costs, was more than $9 billion.
		"London is vulnerable to flooding — be it from the Thames tide, from rivers as a result of heavy rainfall, or from our drainage system," said Roger Evans, the former chairman of a committee on the issue.
	www.sfgate.com /cgi-bin/article.cgi?f=/n/a/2005/09/06/international/i073840D83.DTL (630 words)

	London, Fritz (Wolfgang) - Hutchinson encyclopedia article about London, Fritz (Wolfgang)
		In 1930 his quantum mechanical interpretation of the Van der Waals intramolecular forces made them known as ‘London forces’.
		Fleeing the Nazis in 1933, London and his physicist brother Heinz London, moved to Oxford, England, where the two developed the London equations on superconductivity in 1935.
		Fritz London moved on to the USA to join the faulty at Duke University in 1939, where he continued to contribute to the study of superfluidity and cryogenics (1939–54).
	encyclopedia.farlex.com /London,+Fritz+(Wolfgang) (219 words)

	[No title] (Site not responding. Last check: 2007-10-29)
		Intermolecular attractive forces are much greater in liquids and solids than in gases because the molecules on average, are much closer to each other than in gases.
		London forces are intermolecular interactions caused by a molecule's instantaneous dipole attracting an induced dipole of another molecule.
		The boiling point of dimethyl ether is lower than ethanol because the intermolecular forces between dimethyl ether molecules are weaker than the intermolecular forces between ethanol molecules.
	www.cs.uni.edu /~chin/gchem2/chpt11-04.doc (617 words)

	The Observer \| UK News \| Olympic bribes row forces London into £15m U-turn
		London's bid for the 2012 Olympic Games suffered a major blow yesterday when it was forced to withdraw a £15 million package of financial 'incentives' which the International Olympic Committee claimed came dangerously close to bribery.
		Rogge demanded that London, Paris, New York, Madrid and Moscow should not become embroiled in a 'bidding war' and told them to remember that the IOC was still recovering from 'a period of excesses, of red carpet treatment' and 'a corruption scandal in Salt Lake City'.
		London has been making ground on Paris, the strong favourite, although Juan Antonio Samaranch, Rogge's predecessor as IOC boss, said last week that the French capital was certain to prevail.
	www.guardian.co.uk /Observer/uk_news/story/0,6903,1469046,00.html (725 words)

	London Dispersion Forces
		The London dispersion force is the weakest intermolecular force.
		The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles.
		A second atom or molecule, in turn, can be distorted by the appearance of the dipole in the first atom or molecule (because electrons repel one another) which leads to an electrostatic attraction between the two atoms or molecules.
	www.chem.purdue.edu /gchelp/liquids/disperse.html (336 words)

	Untitled Document
		The ion-dipole force results from the attraction of an ion of positive or negative charge and the oppositely charged end of the dipole on the polar molecule.
		London dispersion forces occur between atoms or molecules of nonpolar substances.
		So we expect the magnitude of the instantaneous dipoles, and therefore the strength of the London forces, to be greater the greater the number of atoms in a molecule and the larger the atoms.
	intro.chem.okstate.edu /1515SP01/Lecture/Chapter12/Lec2201.html (2390 words)

	London Dispersion Forces (Site not responding. Last check: 2007-10-29)
		Since we know that Coulombic (or electrostatic forces) always exist between positive and negative species, it's not surprising that the electrons of one atom might be slightly attracted by the nuclei of an adjacent atom.
		A second example of the effect of London forces is seen in the boiling points of simple hydrocarbons.
		Because London forces arise from interactions present between all molecules, these forces are always present.
	neon.chem.uidaho.edu /~honors/london.html (369 words)

	Intermolecular Forces
		Intermolecular forces are the forces of attractions that exist between molecules in a compound.
		This temperature is a true measure of the forces of attractions between molecules as molecules separate from one another when they turn from a liquid to a gas.
		Nitrogen monoxide and methanol are polar covalent molecules and thus have dipole-dipole forces.
	cost.georgiasouthern.edu /chemistry/general/molecule/forces.htm (1060 words)

	Intermolecular Forces
		Intermolecular forces are particularly important in terms how molecules interact and form biological organisms or even life.
		Intermolecular forces also play important roles in solutions, a discussion of which is given in Hydration, solvation in water.
		Induced dipoles are responsible for the London dispersion forces.
	www.science.uwaterloo.ca /~cchieh/cact/c123/intermol.html (926 words)

	Bonds-vs-Interactions
		The primary difference between bonds and intermolecular forces is the locations of the areas of charge and the magnitudes of the areas of charge.
		Definition: Intermolecular Forces are electrostatic forces of attraction that exist between an area of negative charge on one molecule and an area of positive charge on a second molecule.
		Because the molecules are polar, the force is either a dipole-dipole attraction or a Hydrogen bond.
	www.bcpl.net /~kdrews/interactions/interactions.html (1237 words)

	Dispersion Forces (Site not responding. Last check: 2007-10-29)
		The London dispersion forces are a universal component of long-range vdW forces and arise from the electronic structure of materials and their optical behavior.
		The close relationship between the London dispersion forces and the material’s chemistry and electronic structure represents an avenue for materials design as has been exploited in ceramics processing and applications.
		Finally, new results on the effects of retardation of the London dispersion interaction at large distances are discussed with an emphasis on novel wetting phenomena such as equilibrium surficial films of water on ice and bimodal wetting/dewetting systems.
	www.lrsm.upenn.edu /~frenchrh/dispersion_forces.htm (266 words)

	intermolecular bonding - van der Waals forces
		The forces of attraction which hold an individual molecule together (for example, the covalent bonds) are known as intramolecular attractions.
		Dispersion forces (one of the two types of van der Waals force we are dealing with on this page) are also known as "London forces" (named after Fritz London who first suggested how they might arise).
		Dispersion forces, for example, were described by London in 1930; dipole-dipole interactions by Keesom in 1912.
	www.chemguide.co.uk /atoms/bonding/vdw.html (1496 words)

	Intermolecular Forces Copy Right by C. Chieh, UoWaterloo
		Forces binding atoms in a molecule are due to chemical bonding.
		The force rises from induced dipole and the interaction is weaker than the dipole-dipole interaction.
		Thus, London dispersion forces are strong for heavy molecules.
	www.science.uwaterloo.ca /~cchieh/cact/c123/intermol2.html (980 words)

Try your search on: Qwika (all wikis)