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Question

What is a delocalized electron?
Asked by: Hilly Hookham-Bassett

Answer

Delocalised electrons are spread across more than one atom. Usually electrons in materials are bound to one atom, and atoms are held together by the interactions of the charges on different atoms. In some cases, electrons can be shared between atoms, and are then called delocalised. In the case of hydrocarbons, delocalisation occurs in Benzene rings, where a hexagon of six carbon atoms has delocalised electrons spread over the whole ring. In metals, electrons are delocalised over the whole crystal structure, and carry currents - the outer electrons of the metal atoms are shared in an electron sea, and are not confined to particular atoms.

To really visualize this you have to think of an electron as a probability cloud, and just see that cloud spread over more than one atom; then it's not such a leap to see a delocalised cloud spread all through a metal. The planetary orbit picture of electrons isn't much use for delocalisation; forget about orbits, and think of clouds instead!
Answered by: Paul Hodgkinson, Physics Undergrad, Cambridge University, UK


Science Quote

'The strength and weakness of physicists is that we believe in what we can measure. And if we can't measure it, then we say it probably doesn't exist. And that closes us off to an enormous amount of phenomena that we may not be able to measure because they only happened once. For example, the Big Bang. ... That's one reason why they scoffed at higher dimensions for so many years. Now we realize that there's no alternative... '

Michio Kaku
(1947-)


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