Question

What is the most significant force that attracts water molecules to each other?

Answer 1

Hydrogen bonding.

Explanation:

Hydrogen bonding occurs where hydrogen is bound to a strongly electronegative element, e.g. `O` or `F`. Both `HF` and `OH_2` have disproportionately high boiling points, and `"H-bonding"` is responsible.

The heteratom polarizes electron density towards itself to give `""^(delta+)H-O^(delta-)-H^(delta+)`; when these dipoles align this is an extra intermolecular force that results in the high boiling point of water and hydrogen fluoride.