Question

The nature of the chemical bond in MgO is:
(A) electrovalent
(B) covalent
(C) dative
(D) polar covalent

Answer 1

Hint: The nature of the chemical bond is decided by the valence electrons of the atoms forming the compound. If one atom has a large number of valence electrons and another has less number of valence electrons, then they form compounds by losing and gaining electrons.

Complete step by step solution:
-Magnesium belongs to group 2 of the periodic table. Its atomic number is 12. The configuration can be understood as $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}$. Oxygen belongs to group 16 of the periodic table. It has an atomic number of 16. Its configuration is $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{4}}$ .
-As the valence electrons are 2 in both magnesium and oxygen, it becomes easier for the magnesium atom to lose its electrons to achieve the noble gas configuration and oxygen atom to gain electrons.
-Metals are those elements which lose their electrons to become stable. Group 2 elements are called alkali earth metals. Non-metals are those elements which gain their electrons to become stable.
-As the bond involves losing and gaining electrons, the type of bond formed will be an ionic bond as it involves the generation of ions- cation and anion. Covalent bonds are formed when the atoms complete their octet by sharing electrons, not by losing/gaining electrons from other atoms.
-The valencies of both the atoms are the same and so the atoms in the compound formed will be present in the same ratio.
-There is a huge difference between the electronegativity values of magnesium and oxygen which makes it possible for 1 atom to lose electrons and the other to gain electrons, thus forming ionic bonds.

Therefore the correct option is (A).

Note: In general, the reaction of group 1,2 and 3 elements with the group 5,6 and 7 elements of the periodic table results in ionic bonding only. This is because one set of groups represents the metals and the other set represents non-metals which have huge differences in their properties.