16.3
Pages 460-463
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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
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Main point- How bad do you want that item?
In chemistry this is electronegativity.
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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)
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Actual values for each atom on page 405
Electronegativity Type of Bond
difference
Example
0.0 – 0.4
Nonpolar
covalent
H-H or
C-H
>0.4-1.9
Polar covalent
H-Cl or
H-F
> 2.0
Ionic
NaCl
H=2.1
Cl = 3.0
F= 4.0
C= 2.5 Na=0.9
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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
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Non-polar animation
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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 -)
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Polar bond animation
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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
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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
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
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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.
16.3
Pages 463-466
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“Intermolecular forces”
means
“Attractions between molecules”
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…
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Van Der Waals Forces
◦ 1) London Dispersion forces
◦ 2) Dipole-dipole interactions
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3) Hydrogen bonds◦ The strongest of the intermolecular 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
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The slightly positive part of one molecule will
attract the slightly negative part of another
molecule.
This occurs between two polar molecules.
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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.
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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! 
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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! 
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21) You find the difference in electronegativity
between the atoms.
<0.4 is nonpolar covalent
0.5-1.9 is polar covalent
>2 is ionic
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22) dispersion, dipole-dipole, hydrogen bond
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23)CCl4 has polar bonds, but is not a polar
molecule because of symmetry (it doesn’t have a
(+) and (-) side.
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24)HOOH, BrCl, HBr, H2O
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26)shared bonding electrons, solubility ranges
from high to low, exist as molecules
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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