Organic Chemistry MCAT Practice Exam

What is the term for a carbon species with a negative charge?

1. Carbocation

2. Carbanion

3. Radical

4. Neutral carbon

The correct answer is: Carbanion

The term for a carbon species that carries a negative charge is indeed a carbanion. A carbanion is characterized by having three sigma bonds and a lone pair of electrons on the carbon atom, which gives it a formal negative charge. This species is nucleophilic and often plays a significant role in various organic reactions, as it can attack electrophiles. Carbocations, on the other hand, refer to carbon species with a positive charge, which is the opposite of a carbanion. Radicals contain an unpaired electron, indicating a neutral charge but high reactivity due to the presence of this unpaired electron. Neutral carbon generally refers to a carbon atom that lacks any formal charge, thus does not fit the definition of having a negative charge. Therefore, the correct association of a negatively charged carbon compound is firmly established as a carbanion.