Bonding, Molecular Shape & Structure

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The ease with which an external electric field can induce a dipole (alter the electron distribution) with a molecule is referred to as the "polarizability" of that molecule

The greater the polarizability of a molecule the easier it is to induce a momentary dipole and the stronger the dispersion forces

Larger molecules tend to have greater polarizability

Their electrons are further away from the nucleus (any asymmetric distribution produces a larger dipole due to larger charge separation)

The number of electrons is greater (higher probability of asymmetric distribution)

thus, dispersion forces tend to increase with increasing molecular mass

Dispersion forces are also present between polar/non-polar and polar/polar molecules (i.e. between all molecules)

Slide 54

Group 4A hydrides

Groups 4, 5, 6A hydrides

Van der Waals forces are made of dipole-dipole and London dispersion forces