How do Sodium and chlorine combine?
Sodium (metal) and chlorine (non-metal) form via an ionic bond. Sodium has 11 protons and 11 electrons. In its valence (outermost) shell, it has only one. Chlorine has 17 electrons and 17 protons; 7 electrons in its valence shell. Sodium loses that 1 valence electron and becomes negatively charged, chlorine picks it up and becomes positively charged. Then the they are attracted to each other. In most or all ionic bonds, there is some degree of covalent bond. The bond releases energy which allows the reaction to take place. They structure formed is into a cubical crystal structure. (think rock salt - check out the sodium chloride link). Each ion (na+ and cl-) is surrounded by six of the other ions in the cube.