1. The Nature of Covalent Bonding Objectives: 1. Describe the characteristics of a covalent bond. 2. Describe the difference between polar and nonpolar covalent bonds. Key Terms: Molecule, molecular substance, molecular formula, structural formula, Lewis structure, unshared pair, single covalent bond, double covalent bond, triple covalent bond, polar, nonpolar

2. Bond Types - Single Single bonds – Octet Rule: Atoms of non-metals will share electrons with each other to fill their valence orbital shells. – any atom needing one valence electron will ALWAYS form a single bond » H & group 7A can form 1, » 6A can form 2 » 5A can form 3 » 4A can form 4

3. Bond Types - Double Double Covalent bonds – atoms that need 2 or more valence electrons can form double bonds group 6A can form 1, group 5A can form 1 (+ 1 single bond) group 4A can form 2

4. Bond Types - Triple Triple Covalent bonds – atoms that need 3 or more can form a triple bond group 5A can form 1 group 4A can form 1 (+ 1 single bond)

5. Coordinate covalent bonds Coordinate covalent bonds are covalent bonds where the electrons are donated by a single atom

6. Other interesting facts regarding covalent bonds Unshared electron pairs – any pair of electrons not used in bonding is considered unpaired – adds to the polarity of a molecule Bond Dissociation Energy – the energy required to break a covalent bond – greater as the number of bonds increases (higher in triples than doubles or singles)

7. Exceptions to Octet Exceptions to the octet rule – since covalent bonds make use of shared electrons some molecules form that do not follow the octet rule