London dispersion forces

Examples of London dispersion forces in the following topics:

• Dispersion Force

  • These London dispersion forces are often found in the halogens (e.g., F2 and I2), the noble gases (e.g., Ne and Ar), and in other non-polar molecules, such as carbon dioxide and methane.
  • London dispersion forces are part of the van der Waals forces, or weak intermolecular attractions.
  • London dispersion forces allow otherwise non-polar molecules to have attractive forces.
  • There are two kinds of attractive forces shown in this model: Coulomb forces (the attraction between ions) and Van der Waals forces (an additional attractive force between all atoms).
  • Explore the role of size and shape in the strength of London dispersion attractions.

• The Effect of Intermolecular Forces

  • At high pressures and low temperatures, intermolecular forces between gas particles can cause significant deviation from ideal behavior.
  • Intermolecular forces describe the attraction and repulsion between particles.
  • At high pressures, gas particles are forced into close proximity with one another, causing significant intermolecular interactions.
  • When the weight of individual gas molecules becomes significant, London dispersion forces, or instantaneous dipole forces, tend to increase, because as molecular weight increases, the number of electrons within each gas molecule tends to increase as well.
  • At high pressures and low temperatures, these attractive forces can become significant.

• Cycloalkanes

  • Cycloalkanes, like alkanes, are subject to intermolecular forces called London dispersion forces.

• Introduction to Bonding

  • They are related to weaker intermolecular forces, such as dipole-dipole interactions, the London dispersion forces, and hydrogen bonding.
  • The weaker forces will be discussed in a later concept.
  • Chemical bonds are the forces of attraction that tie atoms together.

• Dipole-Dipole Force

  • Intermolecular forces are the forces of attraction or repulsion which act between neighboring particles (atoms, molecules, or ions).
  • These forces are weak compared to the intramolecular forces, such as the covalent or ionic bonds between atoms in a molecule.
  • Instantaneous dipole-induced dipole forces or London dispersion forces: forces caused by correlated movements of the electrons in interacting molecules, which are the weakest of intermolecular forces and are categorized as van der Waals forces.
  • In this video, Paul Andersen describes the intermolecular forces associated with dipoles.
  • An important type of dipole-dipole forces are hydrogen bonds.

• Binding Energy and Nuclear Forces

  • Nuclear force is the force that is responsible for binding of protons and neutrons into atomic nuclei.
  • The nuclear force is the force between two or more component parts of an atomic nuclei.
  • The nuclear forces arising between nucleons are now seen as analogous to the forces in chemistry between neutral atoms or molecules (called London forces).
  • These nuclear forces are very weak compared to direct gluon forces ("color forces" or "strong forces") inside nucleons, and the nuclear forces extend over only a few nuclear diameters, falling exponentially with distance.
  • Like London forces, nuclear forces also stop being attractive, and become repulsive when nucleons are brought too close together.

• The Boston Massacre and Military Occupation

  • Acting Governor Thomas Hutchinson was summoned to the scene and was forced by the movements of the crowd into the council chamber of the State House.
  • From its balcony he was able to minimally restore order, promising that there would be a fair inquiry into the shootings if the crowd dispersed.
  • Both sides published pamphlets that told strikingly different stories, which were principally published in London in a bid to influence opinion there.

• Biofilms

  • These first colonists initially form a weak, reversible adhesion to the surface via van der Waals forces.
  • Dispersal of cells from the biofilm colony is an essential stage of the biofilm life cycle.
  • Dispersal enables biofilms to spread and colonize new surfaces.
  • Enzymes that degrade the biofilm extracellular matrix, such as dispersin B and deoxyribonuclease, may play a role in biofilm dispersal.
  • Stage 1: initial attachment; stage 2: irreversible attachment; stage 3: maturation I; stage 4: maturation II; stage 5: dispersion.

• Steric Effects

  • When two neutral atoms (A & B) are close enough to detect each other, they experience an attraction due to dispersion forces.

• Restoration of the Stuarts

  • The Committee of Safety sent Lambert with a large force to meet George Monck, who was in command of the English forces in Scotland, and either negotiate with him or force him to come to terms.
  • Lambert's army began to desert him and he returned to London almost alone.
  • Monck marched to London unopposed.
  • In March 1660, Lambert was sent to the Tower of London, from which he escaped a month later.
  • Charles entered London on May 29, his birthday.