1. 4.4 Polarity and Naming Molecular Compounds Objectives1:g,h; 3:c-e
Chemistry

2. Essential Questions
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?

3. 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

4. Electronegativity What determines if electrons are shared equally?
Electronegativity 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

5. Polar or Nonpolar? (cont)
Electronegativity Difference
Type of Bond
0-.4
Nonpolar covalent
.5-1.9
Polar covalent
2.0 or greater
Ionic bond

6. Polar or Nonpolar? Identify if the following are polar or nonpolar H-H
O-H
P-Cl
F-N
Br-I

7. Polar Bonds
In polar bonds the electrons spend more time on the more electronegative element because it is “hogging” the electrons
In an H-Cl the Cl is the more electronegative so the electrons spend more time with it than with the H

8. 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

9. Polar Bonds (cont)
The partial charge can be shown with a Greek symbol () delta or special arrows
Larger
electroneg #
Smaller electroneg #
Positive
Negative
Smaller electroneg #
Larger
electroneg #

10. Polar Bonds (cont)
Draw Lewis structures for the following including polarity arrows/symbols
CH2Cl2
NO2+
GeTeBr2
ClF
Si2H4 (contains Si-Si bond)

11. Naming Covalent Compounds
Number
Prefix 1
Mono- 2
Di- 3
Tri- 4
Tetra- 5
Penta- 6
Hexa- 7
Hepta- 8
Octa- 9
Nona- 10
Deca-
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

12. Naming Covalent Compounds (cont)
Name the following CO
SiO2
N2Se
P2O4
SI2
ClF
C2H4

13. Naming Covalent Compounds (cont)
Write the formulas for the following:
Octacarbon octahydride
Diphosphorous trinitride
Carbon disulfide
Bromine monofluoride

14. Essential Questions
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?

15. 4.4 Tracked Assignment
Worksheet