1. 11/24 I’m home with my baby today
because my mother-in-law had to go home ;)
But we are still learning!
Sit in your assigned seat, 5th period!

2. Over Thanksgiving Break
No homework
Spend time with the people you love

3. Plan for today Go over homework answers
Get a reminder on polar bonds and polar molecules
Complete a station ‘activity’

4. Homework answers – show your lewis structure to the sub to get homework credit

5. Update your chart with the angles shown in green

6. DO NOT TAKE NOTES These slides are posted on the website
Just listen and try to understand
Ask questions
I mean, you can write down a bit if you really want to. I don’t think you need to, though….

7. What makes a molecule polar?
That depends on the polarity of the bonds in the molecule AND the arrangement of those bonds (shape of the molecule)

8. Nonpolar Covalent Bonds
Covalent bonding involves sharing electrons between atoms.
Nonpolar covalent bond – equal sharing of electrons between two atoms.
Both atoms have same attraction for shared pair (they have the same electronegativity or very close).
Example: H – H

9. Polar Covalent Bonds
Polar covalent bond – unequal sharing of electrons between atoms.
One atom has greater attraction for shared pair. (Think: Tug – of – War).
Example: H – Cl
This creates partial (d) charges on each atom in the bond. The atom with the higher electronegativity has the partial negative charge.

10. We have been talking about whether or not the bonds were polar
Now lets talk about whether or not the molecule is a polar as a result of the polar bonds

11. Molecular Polarity
Of course, if you have a molecule with only one nonpolar bonds (because it’s the same atoms), that molecule will be a NONPOLAR MOLECULE regardless of the shape
Like H2
Like ozone, O3

12. But what if the bonds are polar? Does that mean the molecule is polar?
Not necessarily….

13. Nonpolar Molecules
Molecules with polar bonds do not always create polar molecules.
Example: CCl4
Shape is tetrahedral.
Because the polar bonds are spread out symmetrically in space, this has the net effect of cancelling each other out.
CCl4 is a nonpolar molecule.

14. Again, whenever polar bonds are symmetrically arranged, they produce nonpolar molecules.
Another example: CO2
Hey physics people, think of a molecule as being nonpolar when the vectors add to zero  +

15. If the polar bonds are arranged asymmetrically, the molecule is polar.
For example, see how there are hydrogen atoms on one side of the ammonia molecule and no hydrogen atoms on the other side? POLAR

16. CHCl3 is commonly known as chloroform.
Are the bonds polar?
Yes!
Chlorine is more electronegative than carbon. (ΔEN=0.61)
Carbon is more electronegative than Hydrogen. (ΔEN=0.30)
Is this molecule polar?
Yes! Because there are different differences in electronegativity (the ΔEN’s are different)
FYI: anytime you have two different atoms attached to the same central atom, the molecule will be polar.

17. SNAP Symmetrical Nonpolar Asymmetrical Polar
Just remember “SNAP”
SNAP Symmetrical Nonpolar Asymmetrical Polar
Molecular polarity is determined by the shape and distribution of charge in the molecule. To make your life easier, just look the atoms.
If the noncentral atoms on the molecule are different, the molecule is polar. Example: CHCl3
If the atoms in the molecule are the same and arranged symmetrically, the charges are balanced by each other. The molecules are considered to be nonpolar. CH4
However, if the molecule is asymmetrical, it is considered to be polar. NH3
So if it is lopsided, it is polar. If it is balanced, it is nonpolar.

18. You need
A piece of paper and a pencil/pen
Your chart with bond angles

19. Station Review/Notes You will complete a station review/notes activity
You will work with your FACE partner
If you don’t have a face partner, pair up with someone else who also doesn’t have a face partner
If there is an odd number, you can work in a group of 3

20. Station Review/Notes If there are two pages at a station
If they are numbered (1 and 2), do 1 first
If there are no numbers, do them in any order
You can do the 8 stations in any order EXCEPT
Do station 1 before station 2
You will be
Taking notes (if it’s stuff you know, don’t write it down; if you didn’t remember it or it is new, take notes)
Doing practice problems
Learning information
Reviewing information
Stations 1,3,and 7 have answers on yellow paper hanging on the far left board
Work until bell rings; you should get done with at least 5 of the stations (we will finish next time)

21. Do not present the slides that follow

22. Copy down the flow chart below
Determine if the following are polar or nonpolar
BI3
ClO2F
Carbonate
Phosphite
Water
Ammonia
Carbon dioxide