1. Polar and nonpolar covalent bonds and molecules
16.3
Pages

2. Vocabulary Polar Nonpolar Dipole
All have the word “pole” in it, meaning “a part of a system that has opposite positions”
Ex: North Pole and South Pole refers to opposite locations and magnetic fields on earth.
In chemistry Polar refers to oppositely charged sides of a molecule

3. Is sharing always equal?
Main point- How bad do you want that item?
In chemistry this is electronegativity.

4. Electronegativity determines the bond type
We know the shortcuts for finding out the type of compound and bond formed.
Metal with non-metal = ?
Metal with metal = ?
Non-metal with non-metal = ?
This shortcut is really based on electronegativity (how much does one atom want the electrons of the other atom)

5. Electronegativity chart
Actual values for each atom on page 405
H=2.1 Cl = F= C= 2.5 Na=0.9
Electronegativity difference
Type of Bond
Example
0.0 – 0.4
Nonpolar covalent
H-H or
C-H
>
Polar covalent
H-Cl or
H-F
> 2.0
Ionic
NaCl

6. Nonpolar covalent bonds
When both atoms pull on the electrons equally, the electrons are shared equally.
This happens when both atoms are the same (H2, O2, N2, Cl2, F2, Br2, I2)
It also happens when both atoms have very similar electronegativity values
Ex: C-H, C-C
2nd period ended here

7. Non-polar animation

8. Polar covalent bonds
When the two atoms pull on the electrons unequally.
The more electronegative atom will pull harder and acquire a slight negative charge
The less electronegative atom will pull less and acquire a slight positive charge
This is denoted by a delta (delta +, delta -)

9. Polar bond animation

10. Polar molecules
A molecule with one side slightly positive and the other side slightly negative
HCl HF CO
H20
NH3
Not polar:
CH4 does not have any polar bonds
CO2 even though it has polar bonds

11. General Rule for identifying bonds as polar or nonpolar
Same atoms on bond = non-polar bond
C and H = non-polar bond
Every other combination usually polar
Sure solution: Look up electronegativities on page 405 and compare to table on page 463

12. HW: Fill out the table below Use the charts on p.405 and p.463
Bonded atoms
Difference in electronegativity
Polar or nonpolar covalent bond?
H - H
2.1 – 2.1 = 0
Non-polar
H - C
H - O
H - N
C – C
C - O
C - N
S - Cl
O - N
P - F
Br - Br

13. What does the term “likes dissolve likes” mean in regards to polarity?
Likes dissolve likes is a phrase that tells you which molecules will mix and which will not.
Polar dissolves polar
Nonpolar dissolves nonpolar
Polar will not mix with nonpolar
Demonstrate with a bottle that has oil and water in it
Demonstrate with two beakers, one water, one oil, and 2 cubes of sugar in each one.

14. The 3 intermolecular forces
16.3
Pages

15. What does the prefix “inter” mean?
“Intermolecular forces”
means
“Attractions between molecules”

16. Intermolecular attractions
Atoms bond to have complete outer orbitals
When they get there, they stop bonding and become the compound they become
If only covalent bonds existed, each little molecule would be completely independent and every molecular compound would be a ?
Gas!
We would have no liquid!!! 
So there must be OTHER
interactions taking place
between molecules…

17. The 3 weak intermolecular forces/attractions
Van Der Waals Forces
1) London Dispersion forces
2) Dipole-dipole interactions
3) Hydrogen bonds-
The strongest of the intermolecular forces

18. London Dispersion forces
The electrons of a
molecule will shift to one
side, creating a temporary
dipole. This dipole will
cause the other molecule
to create a dipole as well
and attraction will occur for
a very short time.
This occurs between
nonpolar molecules

19. Dipole-dipole forces
The slightly positive part of one molecule will attract the slightly negative part of another molecule.
This occurs between two polar molecules.

20. Hydrogen bonding The strongest of the 3 intermolecular forces
A hydrogen covalently bonded to N, O, or F will be very electron deficient ( +)
It will become attracted
to an unshared pair
of a different molecule.
2nd period ended here: review idea of H-bond being an H bonded to either NOF, attracted to an unshared pair of another molecule

21. Why does this matter? 1) Non-polar vs polar
Polarity explains why water and oil do not mix! 
Oil is non-polar, Water is polar
Polarity explains why water dissolves ionic compounds! 
1st period stopped with non-polar vs polar, ask them to know this (this is the real application of the theory)

22. Why does this matter? 2) Intermolecular forces
Explain why liquids and solids exist! 
Explains the melting and boiling points of molecular compounds.
Hydrogen bonding explains why water has such high surface tension! 
Helps DNA and proteins take the
shapes that they take! 
1st period stopped with non-polar vs polar, ask them to know this (this is the real application of the theory)

24. HW:
21) You find the difference in electronegativity between the atoms.
<0.4 is nonpolar covalent
is polar covalent
>2 is ionic
22) dispersion, dipole-dipole, hydrogen bond
23)CCl4 has polar bonds, but is not a polar molecule because of symmetry (it doesn’t have a (+) and (-) side.
24)HOOH, BrCl, HBr, H2O
26)shared bonding electrons, solubility ranges from high to low, exist as molecules

25. Polar bond – a covalent bond where electrons are shared unequally
The more electronegative atom is slightly negative
The less electronegative atom is slightly positive
Non-Polar bond –a covalent bond where electrons are shared equally
Both atoms have similar or identical electronegativity
Dispersion – weak forces caused by the random motion of electrons
The only attractions non-polar molecules can have
Dipole-dipole – attractions between polar molecules
The slightly positive end of one molecule attracts the slightly negative end of another
Hydrogen bond – an attraction where a hydrogen (that is bonded to an N, O, or F) is attracted to an unshared pair of electrons on another molecule.
The strongest intermolecular attraction of the three