There are three bond pairs and one unshared pair of electrons surrounding an atom. Which of the following molecules fits this description? HF H2O CH4 NH3

NH3

Explanation:

HF is wrong

It is an ionic and not a covalent compound

H2O is wrong

The oxygen atom has 6 valence electrons. If the two oxygen atoms take one electron each, there would be 2 bond pairs and 4 electrons I. e 2 non bonding pairs available

CH4 is wrong

Carbon has 4 valence electrons, this can be taken by each hydrogen atom

NH3 is correct

Nitrogen has 5 valence electrons. The hydrogen atoms take one electron each leaving a single pair of electron on the central nitrogen atom. This gives three bond pairs and one unshared pair