1. Synapse – DO NOT BEGIN ON THE HALF-SHEET YET  11/9/11 Lewis dot structures  EQ: How do you draw covalent compounds?  Write chemical formulas for the following molecules.  antimony tribromide  hexaboron monosilicide  chlorine dioxide  hydrogen moniodide  iodine pentafluoride  dinitrogen trioxide  phosphorus triiodide  sulfur monoxide  carbon tetrabromide  selenium trifluoride SbBr 3 B 6 Si ClO 2 HI IF 5 N2O3N2O3 PI 3 SO CBr 4 SeF 3

2. Synapse EQ: How do we draw Lewis dot structures and what are polar covalent and non polar covalent compounds? Write the names for the following compounds – NaCl – H 2 0

3. Lewis Dot Structures Why do elements bond with other elements? What determines what will bond with the other elements?

4. Review: Valence Electrons Find out which group (column) your element is in. This will tell you the number of valence electrons your element has. You will only draw the valence electrons.

5. Review: Lewis Structures for Elements 1)Write the element symbol for phosphorous. 2)Phosphorous is in the 5 th group, so it has 5 valence electrons. 3)Starting at the right, draw 5 electrons, or dots, counter-clockwise around the element symbol.

6. Review: Lewis Structures for Elements BEGIN ON YOUR HALF-SHEET On your paper, try these elements on your own: a)H b)C c)O d)N e)Cl

7. Review: Lewis Structures for Elements

8. One Step Further: Calculate Valence Electrons Total number of valence electrons = sum of the valence electrons from each atom H2:H2: H 2 = 1 valence electron x 2 atoms = 2 valence electrons – 2 total electrons H 2 O: H 2 = 1 valence electron x 2 atoms = 2 valence electrons O = 6 valence electrons – 2 + 6 = 8 total

9. One Step Further: Calculate Valence Electrons Total number of valence electrons = sum of the valence electrons from each atom CH 4 : C = 4 valence electrons H 4 = 1 valence electron x 4 atoms = 4 valence electrons – 4 + 4 = 8 total NH 3 : N = 5 valence electron H 3 = 1 valence electron x 3 atoms = 3 valence electrons – 5 + 3 = 8 total

10. Before We Begin Two Rules to Know 1.Total # of valence electrons – count all the valence electrons 2.Octet Rule – every atom should have 8 electrons (an octet). Duet Rule – Hydrogen & helium should have 2 electrons (a duet).

11. 3D Geometry Molecules have shapes that can be predicted using Lewis Dot Structures. Most molecules are not flat but rather are 3D shapes that serve various functions on the planet and in our bodies.

12. Structures In a molecule, there are 2 types of atoms: – central – bonded to more than one other atom – terminal – bonded to only one other atom

13. Steps to Draw Lewis Dot Structures 1.Add up all the valence electrons for the compound. 1. Total number of valence electrons: H 2 O (2 x 1) + 6 =8

14. Steps to Draw Lewis Dot Structures 1.Add up all the valence electrons for the compound. 2.Find the central atom. Draw the structure.

15. Steps to Draw Lewis Dot Structures 1.Add up all the valence electrons for the compound. 2.Find the central atom. Draw the structure. H O H

16. Steps to Draw Lewis Dot Structures 1.Add up all the valence electrons for the compound. 2.Find the central atom. Draw the structure. 3.Put single bonds between atoms. H O H

17. Drawing Lewis Dot Structures 1.Add up all the valence electrons for the compound. 2.Find the central atom. Draw the structure. 3.Put single bonds between atoms. 4.Fill in all the dots so all atoms have 8 and H has 2.

18. Dot structure for H 2 O H O H 2 electrons 2 electrons 4 electron 8 electrons

19. Drawing Lewis Dot Structures 1.Add up all the valence electrons for the compound. 2.Find the central atom. Draw the structure. 3.Put single bonds between atoms. 4.Fill in all the dots so all atoms have 8 and H has 2. 5.Count the dots. Do they add up to the number of valence electrons? (Remember 1 bond = 2 electrons)

20. Dot structure for H 2 O H O H 4 shared electrons 4 paired electrons = 8 total electrons

21. CH 4 C = 4 electrons H 4 = 1 electron x 4 = 4 electrons – Total: 4+4 = 8 valence electrons C HH H H Steps for Lewis Dot 1.Valence electrons 2.Central atom 3.Single bonds 4.Octet dots 5.Recount electrons

22. NH 3 N = 5 electrons H 3 = 1 electron x 3 = 3 electrons – Total: 5+3 = 8 valence electrons N HH H Steps for Lewis Dot 1.Valence electrons 2.Central atom 3.Single bonds 4.Octet dots 5.Recount electrons

23. CCl 4 C = 4 electrons Cl= 7 electrons x 4 = 28 electrons – Total: 4+28 = 32 valence electrons C Cl Steps for Lewis Dot 1.Valence electrons 2.Central atom 3.Single bonds 4.Octet dots 5.Recount electrons

24. Now What? Classwork/Homework: – Finish Worksheet including the “Predicted Structure” column – We’ll fill in the “Corrected Structure” column tomorrow THEN DO THE WORKSHEET ON MY LAB TABLE!!!