In the very beginning of the school chemistry course, we are told of NaCl as an archetypal ionic compound. Being less electronegative, sodium loses its electron to chlorine, which, following the "octet rule," thus acquires the 8-electron electronic configuration of a noble gas. All the rules predict NaCl to be the only possible compound formed by chlorine and sodium. Chemists have now discovered new sodium chlorides that call for revision of textbook chemistry.