Transcript 4.5 Polarity and Naming Molecular Compounds Objectives S4

4.5 Polarity and Naming
Molecular Compounds
Objectives S4:4-5, S6:3-4
Chemistry
Essential Questions




What is polarity?
What is the difference between a polar and
nonpolar bond?
How can you tell if a bond is polar or not?
How do you name a covalent/molecular
compound?
Types of Covalent Bonds




There are two types of covalent bonds: polar
and nonpolar
The different types exist because atoms do
not share electrons equally
When electrons are shared equally it is a
nonpolar bond
When electrons are not shared equally it is a
polar bond
Electronegativity




What determines if electrons are shared
equally?
Electronegativity which is the ability to attract
electrons in a chemical bond
The greater the difference in electronegativity
the more polar the bond becomes
p 177 has the table of electronegativity
Polar or Nonpolar? (cont)
Electronegativity Type of Bond
Difference
0-.40
Nonpolar covalent
.41-1.99
Polar covalent
2.00 or greater
Ionic bond
Polar or Nonpolar?






Identify if the following are polar or nonpolar
H-H
O-H
P-Cl
F-N
Br-I
Polar Bonds


In polar bonds the
electrons spend more
time on the more
electronegative element
because it is “hogging”
the electrons
Cl is the more
electronegative so the
electrons spend more
time with it
Polar Bonds



What is going to happen to the charges of the
atoms in a polar bond?
The more electronegative will gain a partial
negative charge and the least electronegative
will have a partial positive charge
The partial charge can be shown with a
Greek symbol () delta or special arrows
Polar Bonds (cont)
Positive
Smaller
electroneg #
Negative
Larger
electroneg #
Naming Covalent Compounds




Use prefixes to
determine how many of
each type of atom
Chart is on p 269
If first prefix is mono,
leave it off
The last element listed
ends in -ide
Number
Prefix
1
Mono-
2
Di-
3
Tri-
4
Tetra-
5
Penta-
6
Hexa-
7
Hepta-
8
Octa-
9
Nona-
10
Deca-
Naming Covalent Compounds (cont)









Name the following
CO
SiO2
N 2O
P2 O 4
SI2
ClF
CCl2H2
C2H4
Naming Covalent Compounds (cont)





Write the formulas for the following:
Octacarbon octahydride
Diphosphorous trinitride
Carbon disulfide
Bromine monofluoride
Essential Questions




What is polarity?
What is the difference between a polar and
nonpolar bond?
How can you tell if a bond is polar or not?
How do you name a covalent/molecular
compound?
4.5 Tracked Assignment

Worksheet