Ionic Bonds; Salt

Appears in
On Food and Cooking

By Harold McGee

Published 2004

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One kind of chemical bond is the ionic bond, in which one atom completely captures the electron(s) of another, so great is the difference between their electron hungers. Chemical compounds held together by ionic bonds don’t simply dissolve in water; they come apart into separate ions, or atoms that are electrically charged because they either carry extra electrons or gave up some of their electrons. (The term was coined by the pioneer of electricity, Michael Faraday, from the Greek word for “going,” to name those electrically charged particles that move when an electrical field is set up in a water solution.) Salt, our most common seasoning, is a compound of sodium and chlorine held together with ionic bonds. In a solid crystal of pure salt, positively charged sodium ions alternate with negatively charged chloride ions, the sodiums having lost their electrons to the chlorines. Because several positive sodium ions are always in a state of attraction to several negative chloride ions, we can’t really speak of individual molecules of salt, with one particular sodium atom bonded to a particular chlorine atom. In water, salt dissolves into separate positive sodium ions and negative chloride ions.