Question

Magnesium chloride is a salt formed from ionic bonding between one magnesium atom and two chlorine atoms. A magnesium atom has two electrons in its outer (third) shell; chlorine atoms have seven electrons in their outer shell. How many electrons would be in the outer shell of the magnesium once it becomes an ion

Answer 1

Answer:

Outermost shell of magnesium ion has 8 electrons.

Explanation:

Mg + Cl → MgCl2

Mg electronic configuration  = $1s^22s^22p^63s^2$

Cl  electronic configuration = $1s^22s^22p^63s^23p^5$

In the third shell there are two electrons while in Chlorine there are 7 electrons.

The ions formed will be  Mg^+2 and Cl-

Since Magnesium has donated 2 electrons to form Mg^+2 ion now the its ionic electronic configuration becomes  

      Mg^+2 = $1s^22s^22p^6$ ( 2 , 8)

Therefore the outermost shell of magnesium ion has 8 electrons.