2. Why do atoms form bonds? To attain a noble gas configuration. How do atoms form bonds? By gaining, losing, or sharing electrons. Gain or loss of electrons  ionic bonding Sharing of electrons  covalent bonding

3. Covalent Bonding Results from the attraction between the nucleus on one atom and the electrons on another atom.

4. The electrons are shared, but not transferred. Often formed between 2 nonmetal atoms of the same element. If Attractions are greater than Repulsions, a bond is formed.

5. Potential Energy vs. Internuclear Distance Low energy High stability Bonding Systems Non-Bonding Systems

6. Different ways of representing a covalent bond. Compounds with covalent bonds are molecular!

7. Recognizing covalent formulas Covalent bonding occurs between nonmetal atoms. Formulas contain nonmetals.

8. Identify Bond Type from Formula CH 4 Cu SO 2 NaCl H2OH2OH2OH2OCsF Mg Na 2 S Li 3 N CO 2 AgAu CaBr 2 Al 2 O 3 CH 3 OH Al N2O5N2O5N2O5N2O5ZnO Coval Coval Coval Coval Coval Coval Ionic Ionic Ionic Ionic Ionic Ionic Ionic Metal Metal Metal Metal Metal

11. Making a bond Liberates energy! Separate Atoms Molecule

12. A + B  AB + energy A and B are both atoms AB is a molecule In this particular case, no bonds are broken and one bond is formed. Energy is released. The reaction is exothermic.

13. A + B  AB + energy A bond is formed & energy is released. AB has less potential energy than A + B. AB is more stable than A + B

14. Breaking a Bond Absorbs Energy!

15. CD + energy  C + D CD is a molecule; C and D are atoms. One bond is broken; no bonds are formed. This reaction is endothermic. C and D have higher potential energy than CD.

16. Structure of Covalent Compounds They form molecules. The more reactants you have, the more molecules you can make.

17. Representations of Molecules Space-filling model Ball-and-stick model Ball-and-stick and electron cloud

18. Representations of Molecules Lewis Structures of Reaction H 2 = Molecular Formula H-H = Structural Formula. - Represents 1 pair of electrons.