Polarity of Bonds and Molecules Answer Key (CHEM 1405)

Electronegativity difference determines the type of bond.

< 0.3 nonpolar covalent bond

> 0.3 but < 1.7 polar covalent bond

> 1.7 ionic bond

Electronegativities

hydrogen 2.1 calcium 1.0

sulfur 2.5 oxygen 3.5

nitrogen 3.0 iodine 2.5

silicon 1.8 chlorine 3.0

mercury 1.9 carbon 2.5

Formula	Lewis Dot Formula	Type of Molecule (Polar, Nonpolar, Ionic)	Bond Electronegativity Difference	Type of bond (Polar, Nonpolar, Ionic)	Type of Intermolecular Forces Present
1. H₂		Nonpolar	2.1 – 2.1 = 0	Nonpolar	London dispersion forces only
2. SO		Polar	3.5 – 2.5 = 1.0	Polar	London dispersion forces and dipole-dipole forces
3. HI		Polar	2.5 – 2.1 = 0.4	Polar	London dispersion forces and dipole-dipole forces
4. CH₃Cl		Polar	C-H bond: 2.5 – 2.1 = 0.4 C-Cl bond: 3.0 – 2.1 = 0.9	Polar Polar	London dispersion forces and dipole-dipole forces
5. NH₃		Polar	3.0 – 2.1 = 0.9	Polar	London dispersion forces, dipole-dipole forces, and hydrogen bonding
6. CaCl₂		Ionic	3.0 – 1.0 = 2.0	Ionic	N/A Ionic compounds don’t form molecules
7. CO₂		Nonpolar	3.5 – 2.5 = 1.0	Polar	London dispersion forces only
8. O₃		Polar	3.5 – 3.5 = 0	Nonpolar	London dispersion forces and dipole-dipole forces
9. NCl₃		Polar	3.0 – 3.0 = 0	Nonpolar	London dispersion forces and dipole-dipole forces
10. CaO		Ionic	3.5 – 1.0 = 2.5	Ionic	N/A Ionic compounds don’t form molecules