A carbocation is defined as which of the following?

• A. A species containing a positively charged carbon
• B. A carbon-centered radical
• C. A carbonyl compound
• D. A negatively charged carbon

Answer: (A)

A carbocation is a species containing a positively charged carbon atom. This happens when carbon loses enough electrons (or forms bonds in a way that leaves only six electrons around it in its valence shell), giving carbon a formal charge of +1. The positive charge is located on the carbon, which is electron-deficient and typically planar with an empty p orbital, making it highly reactive toward nucleophiles. This is different from a carbon-centered radical, which has an unpaired electron; from a carbonyl compound, which features a C=O double bond; and from a negatively charged carbon (a carbanion), which would carry a negative formal charge.