I am wondering why H2S has only London Dispersion forces and not Hydrogen Bonding?
H2S (hydrogen sulfide) has only London dispersion forces and not hydrogen bonding for a few reasons. To understand this, we need to examine the molecular structure and properties of H2S.
Hydrogen bonding occurs when a hydrogen atom is bonded to an electronegative atom (such as oxygen, nitrogen, or fluorine) and is attracted to another electronegative atom from a neighboring molecule. This type of bonding is stronger than the forces exhibited by molecules that only have London dispersion forces.
Though hydrogen is bonded to sulfur in H2S, sulfur is not considered electronegative enough to form hydrogen bonds. In order to have hydrogen bonding, the electronegativity difference between the hydrogen and the atom it is bonded to needs to be significant. Oxygen, for example, is much more electronegative than sulfur and can form hydrogen bonds with hydrogen atoms.
Furthermore, the molecular structure of H2S is symmetrical with a bent geometry. This arrangement of atoms does not lend itself to the formation of multiple hydrogen bonds or the establishment of a network of hydrogen bonding interactions. In contrast, molecules like water, which have a linear or V-shaped geometry, can form multiple hydrogen bonds due to the arrangement of their atoms.
In summary, H2S does not exhibit hydrogen bonding because sulfur is not electronegative enough, and the molecular arrangement of H2S does not facilitate the establishment of multiple hydrogen bonding interactions. Therefore, the primary intermolecular forces present in H2S are London dispersion forces.