1. Covalent Bonds and Compounds Molecules

2. Three Kinds of Bonds 1. Non-metal to non-metal 2. metal to non-metal 3. metal to metal Covalent Covalent Ionic Ionic Metallic Metallic

3. Why do atoms bond? To achieve stability To achieve stability Stability is achieved when octet rule is satisfied Stability is achieved when octet rule is satisfied

4. Bonds and Electronegativity Electrons are transferred between atoms when the difference in electronegativity between the atoms is quite high. Electrons are transferred between atoms when the difference in electronegativity between the atoms is quite high. The amount of transfer depends on the electronegativity difference. The amount of transfer depends on the electronegativity difference.

5. Bonds and Electronegativity The number 1.67 seems to be the magic number.(Note:1.67 rounds to 1.7) The number 1.67 seems to be the magic number.(Note:1.67 rounds to 1.7) If the electronegativity difference is less than 1.67, the bond is more covalent than ionic. If the electronegativity difference is less than 1.67, the bond is more covalent than ionic. If the electronegativity difference is greater than 1.67, the bond is more ionic than covalent. If the electronegativity difference is greater than 1.67, the bond is more ionic than covalent. Pg. 263 Figure 9-15 Pg. 263 Figure 9-15

6. Electronegativity Difference Covalent < 1.67 Covalent < 1.67 However – 0 -.3 is non-polar covalent 0 -.3 is non-polar covalent. 3 – 1.67 polar covalent. 3 – 1.67 polar covalent There are 7 instances of perfectly covalent bonds (electronegativity difference = 0) There are 7 instances of perfectly covalent bonds (electronegativity difference = 0) H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2 H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2

8. Practice problems 22 Pg. 266 Pg. 266

9. What is a covalent bond? Bond that results from the sharing of electons between nonmetals Bond that results from the sharing of electons between nonmetals Type of bonding found in majority of known compounds Type of bonding found in majority of known compounds Molecule – formed when two or more atoms bond covalently Molecule – formed when two or more atoms bond covalently ***Ex. of molecules – carbohydrates, proteins, fats, DNA, wool, cotton, and synthetic fibers found in clothes you wear all consist of molecules

10. Lewis structures Use electron dot diagrams or Lewis dot diagrams to show how electrons are arranged in molecules Use electron dot diagrams or Lewis dot diagrams to show how electrons are arranged in molecules Ex. HBr Ex. HBr Pg. 244 practice problems 19 use different colors for different atoms Pg. 244 practice problems 19 use different colors for different atoms

11. Covalent bonds Lewis structures Lewis structures Single covalent bonds – single pair of electrons shared Single covalent bonds – single pair of electrons shared Double covalent bond - sharing of two pairs of electrons Double covalent bond - sharing of two pairs of electrons Triple bond – sharing of 3 pairs of electrons Triple bond – sharing of 3 pairs of electrons

12. Nomenclature (naming) Covalent bonds are generally between two non-metals. Covalent bonds are generally between two non-metals. CO CO CO 2 CO 2 - Carbon monoxide - Carbon dioxide

13. Prefixes 1 2 3 4 5 6 7 8 9 - Mon(o) - Di - Tri - Tetr(a) - Pent(a) - Hex(a) - Hept(a) - Oct - Non

14. Nitrogen and oxygen (five molecules) N 2 O N 2 O NO NO N 2 O 3 N 2 O 3 NO 2 NO 2 N 2 O 5 N 2 O 5 - Dinitrogen monoxide - Nitrogen monoxide - Dinitrogen trioxide - Nitrogen dioxide - Dinitrogen pentoxide

15. Metallic Bonds Bonding in metals is due to delocalized electrons. Bonding in metals is due to delocalized electrons. These often exist in what is called a sea of electrons. These often exist in what is called a sea of electrons. Metal atoms Sea of “delocalized” electrons

16. Metallic Bonds This explains many of the properties of metals: This explains many of the properties of metals: Malleable Malleable Ductile Ductile Conducts electricity well Conducts electricity well

17. Alloys Two Metals (and sometimes other substances) bonded (mixed) together. Two Metals (and sometimes other substances) bonded (mixed) together.

18. Alloys

19. Alloys

20. Alloys