Construct an explanation of how sodium and chlorine combine to form sodium chloride. a) chlorine metal loses a valence electron to become a cation and nonmetal sodium gains a valence electron to become an anion. these ions then form a bond through sharing valence electrons. eliminate b) nonmetal sodium loses a valence electron to become a cation and chlorine metal gains a valence electron to become an anion. these ions then form an ionic bond through opposite attraction. c) sodium metal loses a valence electron to become a cation and nonmetal chlorine gains a valence electron to become an anion. these then form a covalent bond through sharing valence electrons. d) sodium metal loses a valence electron to become a cation and nonmetal chlorine gains a valence electron to become an anion. these ions then form an ionic bond through electrostatic attraction.