Question

Sodium reacts very vigorously with water and catches fire. But why doesn't the sodium in common salt do that?
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Answer 1

Answer:

The two parts of the salt exist as ions before being dissociated so no explosive chemical reaction has to take place for them to ionize. ... The sodium cation does not react briskly with water as elemental sodium does. When salt dissolves in water, sodium metal is not formed.

Answer 2

Explanation:

Sodium as an element is looking to donate one of its electrons to achieve a stable outer electron configuration. When it reacts with chlorine, the chlorine takes that electron and it is happy since it has a stable electron configuration and the sodium is happy since it has a stable electron configuration. In that exchange of an electron, the sodium becomes positive since it has given its electron to the chlorine, and the chlorine now has a negative charge since it has an extra electron. And both are now ions.

As an ion, sodium doesn't want to gain or lose any more electrons, so it isn't going to react with anything, including water. It has already reacted.