A carbocation is a positively charged ion that contains a carbon atom with only three bonds instead of the usual four. This results in an electron deficiency, making carbocations highly reactive. They often form during chemical reactions, such as in the process of alkyl halide elimination or alkene addition. Carbocations can be classified based on the number of carbon atoms attached to the positively charged carbon. A primary carbocation has one carbon neighbor, a secondary has two, and a tertiary has three. Tertiary carbocations are generally more stable due to the electron-donating effects of surrounding carbon atoms.