Which of the following compounds are best described using resonance structures ?

Question

Consider all reasonable resonance structures for each compound or ion.

a) ClCCH


b) CO32-


c) C2H4O


d) BrF3


e) C2H6O




you must enter all correct answers in one alphabetical lower case group, e.g., if a) b) and e) are true you would enter abe

Answer 1

The answer is b).

The carbonate has carbon as the central atom and 3 oxygens around it. One of the oxygens have a double bond. But note that any of the other two oxygens can have double bonds as well. Thus, forming resonance structures.

Resonance is not possible on isolated bonds, single or otherwise. Although all other choices have double bonds and lone pairs, the resonance structures formed by moving the electrons are unstable or not favored.