1. Choose the element that has the lower electronegativity:
As or Zn
Ba or Be
N or Ne
Choose the element that has the lower electronegativity:
As or Zn
Ba or Be
N or Ne
Choose the element that has the lower electronegativity:
As or Zn
Ba or Be
N or Ne
Choose the element that has the lower electronegativity:
As or Zn
Ba or Be
N or Ne

2. Rank these elements from highest electronegativity to lowest:
Mg, S, F, H, O, Cs
What are the four most electronegative elements?
Highest F, O, S, H, Mg, Cs Lowest
The four most electronegative elements are F, O, N, Cl

3. Classify these molecules as polar or nonpolar:
H2O
HBr
CF4 F2
CO2
NH3
Polar
Polar
Nonpolar
Nonpolar
Nonpolar
Polar

4. What is a covalent bond? How does it differ
from an ionic bond?
A covalent bond results from the sharing of a pair of electrons between two atoms, while an ionic bond involves the transfer of one or more electrons from one atom to another.

5. Is it possible for a molecule to be nonpolar even though it contains polar covalent bonds? Explain.
Why is CO2 a nonpolar molecule, whereas CO is a polar molecule?
It is possible for a molecule to be nonpolar even though it contains polar bonds. If the molecule is symmetrical, the polarities of the bonds will cancel (in a manner similar to a positive and a negative number of the same size) resulting in a nonpolar molecule. An example is CO2 which is linear and nonpolar.
Both molecules contain polar bonds. CO2 is symmetrical about the C atom, so the polarities cancel. In CO, there is only one polar bond, therefore the molecule is polar.