1. Valence Electrons and Lewis Dot Structures We always have so much to do!

2. What is a Valence Electron? Valence Electron: electron in the outermost energy level of an atom. Are they more important than the rest?? –They’re the ones doing most of the movement during a chemical reaction. So we’re going to need to know how many there are in an atom? –Indeed you are!!

3. Finding Valence Electrons with the Periodic Table It’s super easy! You’ll like it! (For everything but Transition Metals in the Middle) –First step: find the element on the periodic table. –Second step: find the group number on the top of that column. (ignore the 1 in Groups 13-18) –Ta-Da! That’s it! Can we practice?? –Absolutely!

4. Yay Practice! Find the # of valence electrons for: 1.Li 2.P 3.I 4.Ar 5.Ca 6.O

5. Check with your Buddy Compare answers to ONE person next to you!

6. Check It! 1.Li=1 2.P=5 3.I=7 4.Ar=8 5.Ca=2 6.O=6

7. Now What Do I Do With That? We can use number of valence electrons to predict which charge they make when we turn them into an ion. Pop Quiz: what’s an ion?? –An atom that has gained or lost electrons. Octet Rule: most atoms want to be surrounded by 8 valance electrons or 0 valence electrons. (It’s all or nothing)

8. How So? For atoms with LESS than 4 valence electrons, they’re going to lose/give up electrons to form positive cations. For atoms with MORE than 4 valence electrons, they’re going to gain/steal electrons to form negative anions. For atoms with 4 valance electrons, it can go either way. For atoms with 8 valance electrons, there is no change.

9. Example I need to know what ion Aluminum forms. I know that it has 3 valence electrons. Is 3 closer to 0 or 8? So will it gain or lose electrons? How many will it lose to be 0? If it loses electrons, will it be + or -? So I end up with… Al +3 Closer to 0 Lose + All 3

10. Remember This Chart?

11. More Practice! Bet you knew that was coming, too, huh? Predict the ion formed by the following elements: Write the symbol with the charge. 1.Cl 2.B 3.K 4.Ca 5.O 6.Ne

12. Check with your Buddy Compare answers to ONE person next to you!

13. Check It! 1.Cl=Cl - 2.B =B +3 3.K=K + 4.Ca=Ca +2 5.O=O -2 6.Ne=Ne (no change)

14. Now For Lewis Dot Structures! Easy, easy stuff! Step 1: Write the symbol for the element. Step 2: Put ‘dots’ around the symbol to represent valence electrons. Ta-Da! That’s it!

15. See It In Action! Let’s do Carbon. Carbon=C Carbon is in Group 4 = 4 valance electrons Put one on each side!

16. Rules for filling in Dots Maximum 2 dots per side (4 sides = 8 dots) It does not matter which side you start on. You have to fill in each side with one dot before you double up… Example: Sulfur has how many valence e - ? 6 How many dots does it get? 6 S

17. You do some! Draw the Lewis Dot Structures for the following atoms: 1.Oxygen 2.Sodium 3.Fluorine 4.Nitrogen 5.Beryllium

18. Check with your Buddy Compare answers to ONE person next to you!

19. Check It! 1. 2. 3. 4.5. O Na F N Be

20. So Easy, Right? The end. Quiz on this stuff next class so don’t forget everything!