1. 4.5 Polarity and Naming Molecular Compounds Objectives 4:d-e, 6: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 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

5. Polar or Nonpolar? (cont)
Electronegativity Difference
Type of Bond
0-.40
Nonpolar covalent
Polar covalent
2.00 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
Cl is the more electronegative so the electrons spend more time with it

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
The partial charge can be shown with a Greek symbol () delta or special arrows

9. Polar Bonds (cont) Positive Negative Smaller electroneg # Larger

10. 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

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

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

13. 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?

14. 4.5 Tracked Assignment
Worksheet