Answer:
A. Sodium =1
B. Magnesium =2
C. Aluminum =3
D. Silicon =4
Fluorine is a halogen group that needs 1 more electron to become stable. When it forms a compound with other, the number of fluor atoms depends on the valence electron of the couple. Sodium has 1 valence electron while magnesium has 2, aluminum has 3 and silicon has 4