1. Covalent Bonding Table of Contents Lecture/Lab/Activity Date Pg# 22. The Periodic Table9/24/10 47 23. Periodic Def & Trends9/27/10 49 24. Electron config practice10/4/10 51 25. Ions and Oxidation Numbers10/5/10 53 26. Lewis Dot Diagram10/6/10 54 27. Intro to Chemical Bonding10/7/10 57 28. Covalent Bonding10/12/10 61 Objective: The student will practice illustrating Lewis dot diagrams of covalent compounds after recording lecture notes Agenda: Covalent Bonding– Lecture

2. Valence electrons - The e - involved in chemical bonding -These e- are in the outermost “n” level - Represented by the Lewis-electron dot structure Ex. Sulfur [Ne]3s 2 3p 4 Electron configuration S 6 valence e - Lewis-e - dot structure Bond Formation

3. Write the Lewis-e - dot structure for Nitrogen! [He]2s 2 2p 3 Electron configuration 5valence e - NNNN 5 th e - placement is arbitrary Practice Problem

4. Atoms will gain, lose, or share e - until they have 8 valence e - (octet rule). There are exceptions! Ex. He only has 2 valence e -.

5. Covalent bonding: Bonding in which electrons are shared instead of transferred. Occurs between non-metals Low melting & boiling point Covalent Bonds

6. Determining the # of Bonds 1.Total Needed 8 per atom H & He = 2 2.Total Available Count valence electrons 3.Needed – Available = # shared

7. In covalent compounds, atoms share e - to achieve octets for the valence e -. F + FF Bonding Pair Each bonding pair represents a single covalent bond. FF = F2F2 Diatomic Molecule Covalent molecule made up of 2 atoms of the same element F Ex. F 2 formation? Starting Valence e - = 14 Final Valence e - = 14

8. HHHH Write the Lewis-e - dot structure for CH 4. C H C + H H H HC or HHH

9. Write the Lewis-e - dot structure for PCl 3. Cl + PP P or Cl

10. What about ions like ClO 2 - ……how do we draw the Lewis-e- dot structure??? + O + Extra e - from the negative superscript OOCl or OOCl O

11. Multiple Bonds Covalent compounds can share more than one pair of valence e -. Ex. CO 2 + C OO 2 shared e - pairs = double bond COO or C OO

12. Example N 2 NN + NN or 3 shared e - pairs = triple bond NN

13. Write the Lewis-e - dot structure for NO 2 -. OO N + O + O NNOO or

14. Using the concept of electronegativity, we observe that there are two types of covalent bonds. Polar Covalent: unequal sharing of electrons by atoms that creates a small dipole. Nonpolar Covalent: equal sharing of electrons, no dipole created. Types of Covalent Bonds