Answer: One electron
Explanation:
Sodium Na, has atomic number of 11, and a configuration of 2, 8, 1
Chlorine Cl, has atomic number of 17, and a configuration of 2, 8, 7
Thus, to form an ionic bond Sodium transfer its one outermost electron to chlorine.
Hence Sodium becomes Na+ (2 ,8) while Chlorine becomes Cl- ( 2, 8, 8) in NaCl and both have stable octet structure.
