\[\begin{array}{l}\begin{array}{*{20}{c}}{C{H_2} = \mathop C\limits_{\left| {} \right.}  - C{H_3}}\\{\,\,\,\,\,\,\,\,C{H_3}}\end{array}\,\,\,\, + \,\,\,{H^ + } \to \left\langle \begin{array}{l}C{H_3} - \mathop {\mathop C\limits_{\left| {} \right.} }\limits^ +   - C{H_3}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(1)\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}\\\mathop C\limits^ +  {H_2} - \mathop C\limits_{\left| {} \right.} H - C{H_3}\,\,\,\,\,\,\,\,\,\,\,\,(2)\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}\end{array} \right.\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\end{array}\]

Độ bền tương đối của carbocation thường tăng khi bậc của nguyên tử carbon mang điện tích dương tăng. Vậy carbocation (1) bền hơn carbocation (2).