Question

What type of bond forms between a slightly positive hydrogen atom in one molecule and a slightly negative atom in another molecule?

Answer 1

`"An hydrogen bond......."`

Explanation:

An hydrogen bond occurs when hydrogen is bound to a strongly electronegative element, i.e. typically oxygen or fluorine, which polarizes electron density towards itself. Charge separation or polarity occurs to give `""^(delta+)H-O^(delta-)-H^(delta+)` or `""^(delta+)H-F^(delta-)` or `""^(delta+)H-N^(delta-)H_2`.

In condensed phases these dipoles line up to give a quite potent INTERMOLECULAR force; and note that this occurs between molecules. Hydrogen bonding is largely responsible for the elevated boiling points of water, ammonia, and hydrogen fluoride.