Answer to Question #93133 in General Chemistry for Nduduzo

Question

Magnesium is used to line industrial furnance because it has a very high melting point. Which type of bond needs to be broken for magnesium oxide to melt?
A. Metallic
B. Co-ordinate
C. Ionic
D. Covalent

Answer 1

Hence the structure of magnesium oxide crystal MgO (melting temperature is some 2850 C) is predominantly ionic (high difference in Pauling electronegativity (Mg) = 1.2 and (O) = 3.5) the ionic bonding must be broken to transfer solid crystalline MgO to the liquid phase. Thus, the answer is C.

P.S. There is no purely ionic crystals at all. Even NaCl is 96-97 % ionic and other is covalent bonding. It can be estimated with the analysis of inter-atomic distances as well as electron density distribution plots.