# zum Directory-modus

Radicals are atoms, molecules or ions with one or more unpaired electrons. Radicals containing two unpaired electrons are called biradicals, while those with three unpaired electrons are named triradicals.

Most radicals are extremely reactive and cannot be isolated. However, some stable radicals exist. Among these are the nitrogen oxides $NO$ and $NO2$ and biradical molecular oxygen $O2$.

## Recommended Learning Units

This learning unit is a short introduction to radical chain reactions.

This learning unit describes radical substitutions and their mechanism.

### Halogenation of Alkanes30 min.

This learning unit describes the principles, kinetics, and thermodynamics of the radical halogenation of alkanes and it explains the reasons for the different chemical properties of the halogens fluorine, chlorine, bromine, and iodine in radical substitution reactions.