Salt, Part 4: Getting Inside the Salt
Salt is an ionic compound, which means that the atomic elements in salt gain or lose electrons rather than sharing electrons. The chemical notation for salt is NaCl, which indicates that a molecule of salt consists of one atom of sodium (Na) and one atom of chlorine (Cl). By themselves, sodium and chlorine are pretty nasty chemicals. Sodium reacts explosively with water and chlorine (in its gaseous form) was used as a chemical weapon in World War 1. When salt is added to water, the ions immediately dissociate and exist in solution as free ions of sodium (Na+) and chlorine (Cl-). In this ionic form, sodium and chlorine are friendly and gentle and make good friends with us humans. Pure sodium and chlorine can be recovered from a salt water solution by passing a current of electricity between probes immersed in the salt water, causing sodium (Na) to deposit on the cathode probe, while chlorine gas (Cl2) is generated at the anode. This is the method commonly used to create pure sodium metal and chlorine gas for industrial uses.