What kind of forces arise from transient dipoles in atoms that induce transient dipoles
in nearby atoms, produce an attractive force and are significant only over short
distances (~500 pm)?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. London dispersion forces.
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. This force is sometimes called an induced dipole-induced dipole attraction.
The strength of London dispersion forces is relatively weaker than dipole-dipole interactions; however both of these attractions are weaker than ionic or covalent bonds.
- They are a type of intermolecular force acting between atoms and molecules that are normally electrically symmetric; that is, the electrons are symmetrically distributed with respect to the nucleus. They are part of the van der Waals forces.
- This force is sometimes called an induced dipole-induced dipole attraction. London forces are the attractive forces that cause nonpolar substances to condense to liquids and to freeze into solids when the temperature is lowered sufficiently.
Properties of London Dispersive Forces
- Forces are attractive.
- Forces are present between all atoms – polar and nonpolar.
- Larger atoms display stronger forces than smaller ones, i.e., the strength increases down a particular group in the periodic table.
- Cylindrically shaped molecules allow more molecules to come close to one another than spherical ones, thereby increasing their strength
Examples of London Dispersive Forces
London dispersion forces are observed in nonpolar molecules. These include:
- Halogens: fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2)
- Nobel gases: helium (He), neon (Ne), argon (Ar), and krypton (Kr)