Covalent Bonds and Lewis Structures

Covalent Bonds

• Covalent bonds form when atoms share electrons
• Triple covalent bonds involve three shared electron pairs between atoms
• Triple covalent bonds are represented by three lines between atoms in a diagram
• Examples of molecules with triple bonds are nitrogen (N₂) and ethyne (C₂H₂)

Lewis Structure Diagrams

• Lewis structure diagrams show valence electron configuration of atoms in molecules
• Electrons are represented by dots or crosses around the atomic symbol
• Diagrams illustrate the arrangement of electrons surrounding atoms

Polar vs. Non-Polar Covalent Bonds

• Polar covalent bonds form between different types of atoms
• Shared electrons are not equally attracted by both atoms in a polar bond
• Non-polar covalent bonds form between similar atoms
• Shared electrons are equally attracted by both atoms in a non-polar bond

Types of Covalent Bonds

• Pure covalent bond: formed by equal sharing of electrons
• Impure covalent bond: formed by unequal sharing of electrons

Properties of Covalent Bonds

• Impure covalent bonds have a dipole moment and charge build-up
• Pure covalent bonds do not have a dipole moment or charge build-up

Hydrogen Bonds

• Hydrogen bonds occur between charged poles of polar molecules

Bond Pairs and Lone Pairs

• Electrons that form a chemical bond are called a bond pair of electrons
• Non-bonded electrons available on an atom in a molecule are called a lone pair of electrons
• Ammonia (NH₃) has one lone pair of electrons on the nitrogen atom