Notes #14

Notes #14 Polar Bonds and Molecules Honors Chem
1. Covalent Bonds involve electron sharing, but some atoms pull on the electrons more than other
2. If each atom pulls equally, meaning the electrons are shared equally, it is called a nonpolar
covalent bond.
a. Examples: Diatomic elements are on polar covalent. They are two of the same atom.
Each atom pulls the same amount on the electrons. (O2, F2, etc.)
3. Drawing:
4. A polar covalent bond is a covalent bond between atoms in which the electrons are shared
The more electronegative an atom is, the more it attracts electrons.
The atom with the higher electronegativity gains a slightly negative charge.
The atom with the lower electronegativity gains a slightly positive charge.
Electronegativity Trend Review:
e. Examples:
As the electronegativity between the two atoms increases, the polarity of the bond increases.
a. See Table 8.4. If the electronegative difference is greater than 2.0 it forms an ionic
compound (A metal and a non-metal)
6. Which type of bond (nonpolar covalent, polar covalent, or ionic) will form between each of the
following pairs of atoms?
a. N and H ___________________
b. F and F ____________________
c. Ca and Cl __________________
7. Place the following covalent bonds in order from least to most polar.
a. H—Cl, H—Br, H—S, H—C ______________________________________________
8. Polar Molecule: one end of the molecule is slightly negative and one end is slightly positive. In
other word it has two poles  this is a dipolar molecule or DIPOLE.
9. Attractions between Molecules:
a. Intermolecular (between the molecules) are weaker than ionic and covalent bonds.
b. Two types:
i. Van der Waals Forces: the weakest attractions between molecules
ii. Hydrogen Bonds: attractive forces in which hydrogen covalently bonds to a very
electronegative atom, but is also weakly bonded to an unshared electron pair of
another electronegative atom.
1. Example: Water Molecules (Draw it)