How to Determine If the Bond Between Two Atoms Is Polar?

Bonds between two atoms in a compound may be classified as either ionic, polar covalent, or nonpolar covalent. In an ionic bond, one or more electrons are transferred resulting in each atom becoming an ion. The positive and negative charged ions are held together due to the charge of the ions. This is the bonding found between metals and nonmetals. In a covalent bond, the electrons are shared and form the bond between two non-metals. In a polar covalent bond, the electrons are shared unequally due to differences in the electronegativity of the atoms. One example of a polar bond is hydrogen-oxygen bonds in a water molecule. Nonpolar covalent bonds have atoms with similar electronegativities, resulting in even sharing of the electrons.

Things You'll Need

• Pencil
• Paper
• Periodic table of the elements
• Pauling's electronegativity scale

Instructions

1. Identify the elements involved in the bond. A periodic table can aid identification of the elements.

2. Reference the electronegativities of the elements in the bond. A commonly used scale is Pauling's electronegativity scale.

3. Calculate the difference in electronegativity between the two elements in the bond.

4. If the difference in negativity is between 0.5 and 1.7, the bond is polar. Differences less than 0.5 indicate a nonpolar bond, while differences greater than 1.7 indicate an ionic bond.

References

• Virginia Tech: Electronegativity and Polar Bonds
• Elmhurst College: Polar Covalent Compounds

Resources

• Los Alamos National Laboratory's Chemistry Division: Periodic Table of the Elements
• Davidson College Chemistry Resources: Pauling's Electronegativity Scale