| The oxygen atom has a higher EN than the chlorine atom (3.5 on the Pauling scale vs 3.0 for the chlorine atom). Firstly, this should be obvious, given that the chlorine atom is never part of any hydrogen bonding network (EN not high enough), and this relationship between O's EN anf Cl's EN can be rationalised by keeping in mind that chlorine occurs in the 2nd period of the periodic table, while oxygen is in the 1st and subsequently oxygen has a much smaller atomic radius and a greater effective nuclear charge Z. |