Question

the second ionisation enthalpy of magnesium is more than that of first and yet magnesium forms mgcl2 not mgcl ?​

Answer 1

Answer:

Magnesium has a total of 2 electrons in its most outer sub-shell, they "feel" an attraction to the nucleus where the positive charges are,that attractive force is "pulling" on the 2 (3s) electrons. When Magnesium ionizes to Mg + (from 3s2 to 3s1 ) not the attractive force is stronger on that 1 electron. So for every electron that is removed, the next electron requires more energy in order for that electron to be removed.

Mg (Magnesium) tends to form Mg++ ions with two extra unshared electrons.

Cl (Chlorine) tends to form Cl- ions, capturing one electron.

So, it takes two chlorine ions to capture the two extra electrons from the magnesium ion.

Note: these are ionic bonds, not covalent bonds, so the atoms are found more in 2:1 proportions without a distinct molecule, rather than in a molecular form like water or carbon dioxide.