Читать книгу Foundations of Chemistry - Philippa B. Cranwell - Страница 129

1 Silane is a tetrahedral molecule with four Si—H bonds. The electronegativities of silicon and hydrogen are very similar and the molecule is symmetrical, so there is no overall dipole present. This means that the most likely type of interaction between two silane molecules is instantaneous dipole–induced dipole or London dispersion forces.

2 Methanol contains an O—H bond, so there is a large dipole between the carbon and the oxygen and an even bigger dipole between the hydrogen and the oxygen atoms. This can create permanent dipole to permanent dipole interactions. More specifically, because the hydrogen of the O—H bond is bonded to oxygen, methanol can undergo hydrogen bonding with other molecules of methanol, CH3OH.

3 Dichloromethane contains two carbon‐chlorine bonds, which both have a permanent dipole due to the different electronegativities of carbon and chlorine; carbon is δ+ and chlorine δ−. This is a permanent dipole; therefore, the dominant intermolecular force in dichloromethane is permanent dipole–permanent dipole.