1. Ch 9 COVALENT BONDING

2. Covalent bonds • Chemical bond that results from the sharing of TWO electrons

3. Covalent bonds

4. Covalent bonds

5. Covalent bonds

6. Covalent Bonds Balancing Act of Attractive and Repulsive Forces Electrostatic Forces

7. Diatomics • Hydrogen • Nitrogen • Oxygen • Fluorine • Chlorine • Bromine • Iodine • H2 • N2 • O2 • F2 • Cl2 • Br2 • I2

8. Are you Listening???? What is a covalent bond? How is it different from an Ionic Bond. Covalent bonds are the chemical bonds formed when atoms SHARE electrons. T Covalent Ionic Share electrons transfer electrons

9. Lewis Structures • Atomic symbol with valence electrons around it H H

10. Lewis Structures F • Find atomic symbol • Determine number of valence electron • Place electrons alone first • Pair up if needed 7 valence electrons

11. Lewis Structure Practice H • H • O • N • C O C N

12. Valence Electrons Tell us # e to share Paired electrons NOT shared F F

13. Lewis Structure Practice H • H • O • N • C O C N

14. Number of Bonds H H C H H H σ H O H N H H H H

15. What is a single covalent bond? Why does it form? A single covalent bond is the sharing of two electrons by two atoms with each atom contributing one electron to the shared paired. They form to allow atoms to become stable by having access to 8 electrons!!!!

16. Orbitals and Bonding Sigma bonds can form between 2s orbitals 1s , 1p 2p Bonding orbital – region where bonding electrons are likely to be found

17. Multiple Covalent Bonds O O DOUBLE BOND N N TRIPLE BOND

18. Make Me some π

19. Write this down!!! Why do multiple covalent bonds form? They form that so that atoms can have access to 8 electrons. In other words so that atoms can obtain a NOBLE GAS CONFIGURATION

20. Bond Length • Distance between nuclei at the MAX attraction • Units are usually Å • 1Å = 10-10 m 1m = 1010 Å Convert 0.05 m to Å Convert 1.46 Å to m Convert 2.65 Å to nm Convert 123 pm to Å 5.0*108 Å 1.46*10-10 m 26.5 nm 1.23 Å

21. Bond Strength H H O O N N

22. Lowest Energy Distance E N E R G Y Distance

23. Lowest Energy Distance E N E R G Y Distance

24. Lowest Energy Distance E N E R G Y Distance

25. Lowest Energy Distance E N E R G Y Bond Dissociation Energy Distance

26. Almost Done • F2 1.43 Å • O2 1.21 Å • N2 1.10 Å 159 kJ/mol 498 kJ/mol 945 kJ/mol

27. How is bond length related to bond dissociation energy? The shorter the bond the larger the dissociation energy.

28. Energy • Energy is always released when making a chemical bond • Energy is always added when breaking a chemical bond • Need to look at TOTAL ENERGY of a RXN

29. Endo vsExo Exothermic – energy is flowing out Endothermic – energy is flowing into