Radical
A radical is an atom of an element or a group of atoms of different elements that behave as a single unit with a positive or negative charge on it.
![](/community/img/radical-6a95149b2d-800x967.jpg)
Positively charged radicals are called basic
radicals such as Na+, NH4+ etc.
Negatively charged radicals are called acid
radicals such as NO3-, Cl-, etc.
![](/community/img/ammonium-71aeac993e-800x533.jpg)
Basic radicals are also known as cations and acid radicals are known as anions.
![](/community/img/pos-valent-8f73a75f17-800x899.jpg)
Radicals are categorised as monovalent, bivalent, trivalent, etc.
![](/community/img/neg-valent-e606a1f7d1-432x540.jpg)