Covalent Bonding

1. Covalent Bonding Time to SHARE

3. OBJ 1 Define covalent bonding • Definition – Bond formed when electrons are SHARED • Usually occurs between two non-metals

4. Examples • Carbon and Chlorine • C+4 • Cl-1 • Formula • CCl4 • Nitrogen and Hydrogen • N-3 • H+1 • Formula • NH3

5. OBJ 2 - Identify what compounds are covalent based on the placement on the periodic table. Which of the following are covalent? NaCl N2O3 H2O CCl4 MgONH3

6. OBJ 3 - Determine which elements will form diatomic molecules • Diatomic molecules are covalent compounds between two identical elements. • Only certain elements that will do this. • They are: • Hydrogen H2 • Nitrogen N2 • Oxygen O2 • Fluorine F2 • Chlorine Cl2 • Bromine Br2 • Iodine I2

7. OBJ 4 - list prefixes and suffixes used in covalent compound names • We use prefixes based on the # of atoms • # of atoms is determined by the subscript in the formula (H2O) • First element will always have a prefix (Except when we only have 1 then we don’t use a prefix) second element will ALWAYS have a prefix • Note: When a prefix ending in ‘o’ or ‘a’ is added to ‘oxide’, the final vowel in the prefix is dropped.

8. You need to memorize these!

9. H2O Dihydrogen monoxide NH3 Nitrogen trihydride BF3 Boron triflouride Si2O4 Disilicontetroxide OBJ 5 -name covalent compounds given chemical formulas

10. P4O10 Tetraphosphorus decoxide SO2 Sufur dioxide CCl4 Carbon tetrachloride P2O3 Diphosphorous trioxide IF7 Iodine heptaflouride Your turn name the compound

11. OBJ 6 formulate the chemical formula of a covalent compound given the name • This is a little different from ionic compounds • We will USE THE PREFIXES • Examples: • Diphosphorouspentoxide • P2O5 • Nitrogen trichloride • NCl3

12. Your turn • Sulfur hexafluoride • SF6 • Carbon tetrachloride • CCl4 • Dinitrogen pentoxide • N2O5

13. Cl Cl C Cl H H H H Cl N H O So what does it look like?

14. Bell Work - Friday Which system is responsible for producing enzymes that aid in breaking down substances to be absorbed for the body’s growth and repair? A Digestive system B Reproductive system C Respiratory system D Skeletal system

15. Obj 7 Identify shapes based on VSEPR theory • What is VSEPR theory? • Valence Shell Electron Pair Repulsion • Electrons push away from each other

16. Cl Cl C Cl Cl So what does that have to do with shape? • Look at this diagram • What would the electrons be doing to each other? • Repel because they are are the same charge

17. So how would that affect the shape? • This is called a tetrahedral shape

18. The shapes • Paste your handout in your notes • You will need to know these shapes for the test

19. 0 lone pairs 1 lone pair 2 lone pairs

20. So how can you tell what shape it will be? • You need to know the # of electron groups and the # of lone pairs

21. F F F What do you see? • How many electrons are around B now? • Is this okay? • In covalent bonds YES • The # of bonds is the same as the # of valence e- B

22. So lets draw one • Start with the Lewis Dot Diagram

23. So how do you draw the Lewis Dot Diagram? • Determine the central atom • (use electronegativities) • The # of bonds possible is the same as the # of valence e- the central atom has • NOTE THIS IS NOT LIKE IONIC – DON’T ASSUME ONLY 8 ELECTRONS

24. How? BF3 Electronegativity B – 2.0 F – 4.0 Least electronegative is B B

25. Next step • How many valence electrons does it have? • 3 • The lines will represent the bonds that it will make B

26. Next step F • Add your surrounding atoms • Then add electrons around them B F F

27. Your Turn White Board Practice CCl4 H2O O H H Cl Cl C Cl Cl