1. Notes 5-3 Covalent Bonds + - + -

2. COVALENT BOND A force that bonds two atoms together by a sharing of electrons Each pair of shared electrons creates a bond Usually occurs between atoms of non-metals ++ + + + + + + + + Example – Water (H 2 O)Water (H 2 O) - - - - - - - -- - OHH

3. How Covalent Bonds Form

4. The oxygen atom in water and the nitrogen atom in ammonia each have eight valence electrons as a result of forming covalent bonds with hydrogen atoms.

5. How Covalent Bonds Form Double and triple bonds can form when atoms share more than one pair of electrons.

6. Types of Covalent Bonds Different covalent bond types share a different number of electrons Single Bonds Share 2 Electrons Double Bonds Share 4 Electrons Triple Bonds Share 6 Electrons Water (H 2 O)Carbon Dioxide (CO 2 )Nitrogen (N 2 )

7. + + + + + + + + Unequal Sharing (Polar Covalent Bond) Why do you think the two Hydrogen atoms share equally, but the Hydrogen and fluorine do not? + + + Bonded hydrogen atoms showing equal sharing of electrons Hydrogen and fluorine bond with an unequal sharing of electrons The unequal sharing of electrons between two atoms that gives rise to negative and positive regions of electric charge Results from an atom’s electronegativity – the ability to attract electrons to itself Electron Cloud

8. Unequal Sharing of Electrons Fluorine forms a nonpolar bond with another fluorine atom. In hydrogen fluoride, fluorine attracts electrons more strongly than hydrogen does, so the bond formed is polar.

9. Unequal Sharing of Electrons A carbon dioxide molecule is a nonpolar molecule because of its straight-line shape. In contrast, a water molecule is a polar molecule because of its bent shape.

10. Results of Bonding Molecule A neutral group of two or more non-metal atoms held together by covalent bonds Type: Diatomic - molecules consisting of two atoms of the same element bonded together Examples: H 2, F 2, O 2, N 2 Compound A pure substance composed of two or more different elements (atoms) that are chemically combined Examples: CO, NO 2, NaCl

11. Molecule, Compound, or Both? H 2 Hydrogen NO 2 Nitrogen Dioxide Cl 2 Chlorine O 2 Oxygen NO Nitric Oxide CO 2 Carbon Dioxide N 2 Nitrogen H 2 O Water CH 4 Methane

12. Review Guide Pg 130, problems 2a,b,c Pg 137, problems 1a, 2a,b,c Pg 145, problem 2a Pg 163, problems 2a,b,c Pg 165-166, problems 1-3, 5-7, 10, 12, 13, 17, 18, 20 Pg 182, problems 1a,b, 2a,c Pg 189, problems 1a,b, 2b,c Pg 197, problems 1b,c Pg 205-206, problems 1-4, 6, 8, 9, 11, 13, 14, 21-25