Tertiary carbonium ions are the most stable due to hyperconjugation effect and +I effect of methyl group.
The number of carbon groups bonded to the carbon determines the name of the carbocation. On the basis of how many carbon atoms are bound to it, the carbocation can be classified as methyl, primary, secondary, or tertiary carbocation.
- The most stable carbonium ion is said to be the ones that belong to the tertiary carbonium ions category.
- The least stable carbocations are methyl carbocations.