Question

Compare and contrast ionic and covalent bonding. Use sodium chloride and hydrogen chloride as examples of each type of bonding.

Answer 1

Covalent bonding is the sharing of electrons between atoms. This type of bonding occurs between two atoms of the same element or of elements close to each other in the periodic table. This bonding occurs primarily between nonmetals; however, it can also be observed between nonmetals and metals. 

Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively charged anion. Ionic bonds require an electron donor, often a metal, and an electron acceptor, a nonmetal. 

In NaCl, the sodium atom is donating its 1 valence electron to the chlorine atom. This creates a sodium cation and a chlorine anion. Notice that the net charge of the resulting compound is 0.

But in HCl, the electrons are shared in the H-Cl bond, which is why it is covalent. The reason lies in the electronegativity—the difference in electronegativity between H and Cl is too small to be considered ionic.