electron độc thân là gì

From Wikipedia, the không lấy phí encyclopedia

Periodic table with elements that have unpaired electrons coloured

In chemistry, an unpaired electron is an electron that occupies an orbital of an atom singly, rather than vãn 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 vĩ đại contain two electrons (electron pair) with opposite spins. As the formation of electron pairs is often energetically favourable, either in the sườn 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.

Bạn đang xem: electron độc thân là gì

Radicals are uncommon in s- and p-block chemistry, since the unpaired electron occupies a valence p orbital or an sp, sp2 or sp3 hybrid orbital. These orbitals are strongly directional and therefore overlap vĩ đại sườn strong covalent bonds, favouring dimerisation of radicals. Radicals can be stable if dimerisation would result in a weak bond or the unpaired electrons are stabilised by delocalisation. In contrast, radicals in d- and f-block chemistry are very common. The less directional, more diffuse d and f orbitals, in which unpaired electrons reside, overlap less effectively, sườn weaker bonds and thus dimerisation is generally disfavoured. These d and f orbitals also have comparatively smaller radial extension, disfavouring overlap vĩ đại sườn dimers.[1]

Xem thêm: toán lớp 2 kì 1

Xem thêm: đề minh họa hóa 2023

Relatively more stable entities with unpaired electrons vì thế exist, e.g. the nitric oxide molecule has one. According vĩ đại Hund's rule, the spins of unpaired electrons are aligned parallel and this gives these molecules paramagnetic properties.

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 magnetic dipole moment, while an electron pair has no dipole moment because the two electrons have opposite spins ví their magnetic dipole fields are in opposite directions and cancel. Thus an atom with unpaired electrons acts as a magnetic dipole and interacts with a magnetic field. Only elements with unpaired electrons exhibit paramagnetism, ferromagnetism, and antiferromagnetism.


  1. ^ N. C. Norman (1997). Periodicity and the s- and p-Block Elements. Oxford University Press. p. 43. ISBN 0-19-855961-5.