Unpaired electron
In chemistry, an unpaired electron is an electron that occupies an orbital of an atom singly, rather than as part of an electron pair. Each atomic orbital of an atom (specified by the three quantum numbers n, l and m) has a capacity to contain two electrons (electron pair) with opposite spins. As the formation of electron pairs is often energetically favourable, either in the form of a chemical bond or as a lone pair, unpaired electrons are relatively uncommon in chemistry, because an entity that carries an unpaired electron is usually rather reactive. In organic chemistry they typically only occur briefly during a reaction on an entity called a radical; however, they play an important role in explaining reaction pathways.
Radicals are uncommon in s- and p-block chemistry, since the unpaired electron occupies a
Relatively more stable entities with unpaired electrons do exist, e.g. the
The most stable examples of unpaired electrons are found on the atoms and ions of lanthanides and actinides. The incomplete f-shell of these entities does not interact very strongly with the environment they are in and this prevents them from being paired. The ions with the largest number of unpaired electrons are Gd3+ and Cm3+ with seven unpaired electrons.
An unpaired electron has a
References
- ISBN 0-19-855961-5.