If magnesium (metal) has two valence electrons while chlorine (nonmetal) has seven, how many chlorine atoms are needed to form an ionic bond with magnesium?

A. One

B. Two

C. Four

D. Three

b. two chlorine atoms are need

The answer is; B

Since chlorine has 7 valence electrons, it requires one (1) more electron to achieve the stable configuration. (2.8.8) Magnesium, on the other hand, needs to lose two (2) of its valence electrons to achieve a stable configuration (2.8). Therefore, it two chlorine atoms pair up with one magnetism, they will achieve some stability. Each of the chlorine atoms will get one of the magnesium valence electron. This will cause the Mg to have a 2 + charge and the Cl a - charge. They then form an ionic bond.