Question

Which compounds have nonpolar covalent bonds, which have polar covalent bonds, and which have ions? (a) LiF (b) \(\mathrm{CH}_{3} \mathrm{~F}\) (c) \(\mathrm{MgCl}_{2}\) (d) \(\mathrm{HCl}\)

Short answer

Question: Identify the type of bonding in each of the following compounds: (a) LiF, (b) \(\mathrm{CH}_{3} \mathrm{~F}\), (c) \(\mathrm{MgCl}_{2}\), and (d) \(\mathrm{HCl}\). Answer: (a) LiF has an ionic bond, (b) \(\mathrm{CH}_{3} \mathrm{~F}\) has nonpolar covalent C-H bonds and a polar covalent C-F bond, (c) \(\mathrm{MgCl}_{2}\) has ionic bonds, and (d) \(\mathrm{HCl}\) has a polar covalent bond.

Step-by-step solution

(a) LiF - Determine Electronegativity Difference

First, find the electronegativity difference between Li (electronegativity value 1.0) and F (electronegativity value 4.0). \(\Delta \mathrm{EN} = |4.0 - 1.0| = 3.0.\)

(a) LiF - Identify the Type of Bonding

Since the electronegativity difference between Li and F is greater than 1.7, LiF has an ionic bond.

(b) \(\mathrm{CH}_{3} \mathrm{~F}\) - Determine Electronegativity Difference

The molecule \(\mathrm{CH}_{3} \mathrm{~F}\) has two different types of bonds: C-H and C-F. First, find the electronegativity difference between C (electronegativity value 2.5) and H (electronegativity value 2.1) for the C-H bond. \(\Delta \mathrm{EN} = |2.5 - 2.1| = 0.4.\) Next, find the electronegativity difference between C and F for the C-F bond. \(\Delta \mathrm{EN} = |2.5 - 4.0| = 1.5.\)

(b) \(\mathrm{CH}_{3} \mathrm{~F}\) - Identify the Type of Bonding

Since the electronegativity difference between C and H is less than 0.5, the C-H bonds are nonpolar covalent. Since the electronegativity difference between C and F is between 0.5 and 1.7, the C-F bond is polar covalent.

(c) \(\mathrm{MgCl}_{2}\) - Determine Electronegativity Difference

First, find the electronegativity difference between Mg (electronegativity value 1.3) and Cl (electronegativity value 3.0). \(\Delta \mathrm{EN} = |3.0 - 1.3| = 1.7.\)

(c) \(\mathrm{MgCl}_{2}\) - Identify the Type of Bonding

Since the electronegativity difference between Mg and Cl is equal to 1.7, \(\mathrm{MgCl}_{2}\) has ionic bonds.

(d) \(\mathrm{HCl}\) - Determine Electronegativity Difference

First, find the electronegativity difference between H (electronegativity value 2.1) and Cl (electronegativity value 3.0). \(\Delta \mathrm{EN} = |3.0 - 2.1| = 0.9.\)

(d) \(\mathrm{HCl}\) - Identify the Type of Bonding

Since the electronegativity difference between H and Cl is between 0.5 and 1.7, \(\mathrm{HCl}\) has a polar covalent bond.