Tuesday, 31 January 2017

The Exclusion Principle

Schrodinger showed that electrons in atoms could have certain energies, and they could jump between energy levels by emitting or absorbing light energy. His equation was a brilliant success, apart from one obvious question- why didn't all the electrons in an atom just sink to the lowest energy level and stay there?
We don't really know the answer to the question, but, simplifying things somewhat, one can explain it by introducing a rule that says you can't have more than two electrons with the same shape wave in an atom. This means that only two electrons can sink to the lowest energy level in an atom. After that, the electrons have to gradually fill the higher energy levels.
The rule is known as The Pauli Exclusion Principle, after Wolfgang Pauli, the Austrian physicist who first proposed it, in 1925.
The theory also says that two electrons that share the same shape wave in an atom must have opposite spins.

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