1. Warm Up Name the following compound 1.Cl0 2 Give the following formula 2. Disilicon Hexafluoride 3. Carbon tetrachloride

2. Covalent Compounds: Writing Lewis Dot Structures

3. What are the atoms trying to achieve? Octet rule = atoms want 8 electrons in their valence shell Exception #1: Hydrogen and Helium only want 2

4. Covalent Bonding in H 2 H.H. Two hydrogen atoms, each with 1 electron, can share those electrons in a covalent bond. H:H Sharing the electron pair gives each hydrogen an electron configuration analogous to helium.

5. Covalent Bonding in F 2 Two fluorine atoms, each with 7 valence electrons, can share those electrons in a covalent bond. Sharing the electron pair gives each fluorine an electron configuration analogous to neon..... F.F.: :.... F : F : :........

6. ExampleExample C.... F :..... Combine carbon (4 valence electrons) and four fluorines (7 valence electrons each) to write a Lewis structure for CF 4. : F :.... C : F :.... : F :.... : F :.... The octet rule is satisfied for carbon and each fluorine.

7. ExampleExample It is common practice to represent a covalent bond by a line. We can rewrite : F :.... C : F :.... : F :.... : F :...... C F F F F........ : : : :::.. as

8. So… 2 shared electrons can be rewritten as a single line. The line is called a ‘single bond’. TRY IT!! 1.Draw the lewis dot structure for Phosphorus Triiodide 2.Draw it again, this time replacing pairs of shared electrons with a single line.

9. Phosphorus Triiodide P I I I P I I I.... :.. : : : : : : : : : : : : : : : : : : : _ _ _

10. Double bonds Some atoms share more than 2 pairs of electrons between them. You still replace each pair of shared electrons with a line but if two lines are present between 2 atoms, it is called a DOUBLE BOND. C : : : O.. : O..: : Carbon dioxide Try drawing the double bonds for carbon dioxide

11. C : O.. O..: C : : : O.. : O..: : becomes

12. Triple Bonds :::N : C : H :NC H Hydrogen cyanide

13. REMEMBER… The atoms want to have 8 valence electrons! Shared electron pairs can be represented by a line, which shows that the atoms are bonded.

14. Let’s practice! Ethylene Acetylene :::C : C : H H C : : C.. H ::.. H HH Replace the electron pairs by drawing in the bonds

15. Ethylene Acetylene :::C : C : H H CC HH C : : C.. H ::.. H HH C CHHH H