Free radical vs radical cation

What is the difference between a free radical and a radical cation? Are they different thing or do they mean same?




A *radical cation* is simply a *free radical* with a positive charge. Similarly a *radical anion* is a free radical with a negative charge.


In other words, *radical cations* and *radical anions* are subsets of the *free radicals*.


That said, the term *free radical* itself is not entirely clear cut, as illustrated in [this question](https://chemistry.stackexchange.com/questions/440/what-makes-a-radical-free).


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