Why is the formula for magnesium fluoride MgF2 why?

Question

Why is the formula for magnesium fluoride MgF2. In a covalent bonding isn't a atom suppose to have a full outer shell to become more stable? But when 2 fluorine are bonded with the magnesuim it still doesn't give magnesuim a full out shell?

Answer 1

Magnesium fluoride molecules are connected by ionic bonding

Mg2+ Fl- Fl- leading to an overall balanced charge

Answer 2

Mg is a group 2 alkali earth with 2 electrons in its outer shell.

Fluorine is a group 7 halogen with 7 electrons in its outer shell.

Mg  readily loses the two electrons to form th Mg  2+  ion. These two electrons are readily accepted by two F atoms to form 2   F- ions. The Mg has a stable 8 electron outer shell remaining, and the F atom also has a stable 8 electron outer shell. The result is a MgCl2 molecule that ionises in water to form:

MgCl2  <=> Mg 2+  +  2Cl-

Answer 3

Even in covalent each atom has a full outer shell since 1 atom of Mg shares one pair of electrons with each atom of fluorine  

Answer 4

Pretty sure it an Ionic bond...

"guy ss" has it right, fluorine only needs 1 more electron to complete it outer shell while magnesium needs to lose 2. So 2 fluorine atoms are needed to balance the charge.