Covalent Bonding Overview

Covalent Bonds: Basics

• Covalent bonds form when atoms share electrons instead of transferring them.
• Each shared pair of electrons is often represented by a line between atoms.
• Atoms become more stable by sharing electrons to fill their outer (valence) shells.

Example: Oxygen Molecule (O₂)

• Each oxygen atom has six valence electrons and wants eight for stability.
• Two oxygen atoms share two pairs of electrons, forming a double covalent bond.
• This sharing allows both oxygens to “count” eight electrons, achieving a stable configuration.

Example: Water Molecule (H₂O)

• Oxygen has six valence electrons; each hydrogen has one.
• Oxygen forms single covalent bonds with two hydrogens by sharing one electron with each.
• As a result, oxygen appears to have eight valence electrons, and each hydrogen appears to have two.

Polarity in Covalent Bonds

• Oxygen is more electronegative (attracts electrons more strongly) than hydrogen.
• In water, shared electrons spend more time near oxygen, causing a partial negative charge on oxygen and partial positive charges on hydrogens.
• Such bonds with unequal sharing are called polar covalent bonds.

Key Terms & Definitions

• Covalent Bond — a chemical bond where two atoms share one or more pairs of electrons.
• Valence Electrons — electrons in the outermost shell of an atom involved in bonding.
• Electronegativity — the tendency of an atom to attract shared electrons.
• Polar Covalent Bond — a covalent bond where electrons are shared unequally, leading to partial charges.
• Nonpolar Covalent Bond — a covalent bond where electrons are shared equally between atoms.

Action Items / Next Steps

• Review examples of covalent compounds such as O₂ and H₂O.
• Practice drawing electron dot structures for simple molecules.