ABSTRACT
As the water molecule contains two lone pairs of electrons on the oxygen atom, and two polarized hydrogen atoms (see below), each water molecule is able to participate in four hydrogen bonding interactions (Section H1). It can act as an acceptor for two hydrogen bonds, via the lone pairs, and as a donator for two others, through its hydrogen atoms. This matching of donor and acceptor capacity means that water molecules are optimally suited to hydrogen bonding with each other. This is what occurs in liquid (and solid) water. These bonds have to break before water can enter the gas phase.
