Chemistry Questions Molecular Polarity printable pdf download

Chemistry 1/2

Questions 16.2

Molecular polarity

Molecules that share bond electrons evenly are called nonpolar molecules. The diatomic free elements

, N

, O

, F

, Cl

, Br

, and I

are nonpolar because two atoms of the same element always have the same

attraction for the bond electrons. Most other compounds have some amount of unequal sharing of the bond

electrons.

Electronegativity is the measure of the attraction for electrons in a bond. The small nonmetal atoms like

fluorine, oxygen, chlorine, and nitrogen have the highest electronegativity. The 1A group metal atoms (Li – Fr)

have the lowest electronegativity. Electronegativity figures are on the back side of your periodic table in the

upper right hand corner.

You can find out the bond polarity of a bond by subtracting the electronegativities of the 2 atoms in the

bond. There is also a table on the back top of the periodic table that gives the percentage ionic character in the

bond based on the difference in electronegativities. The larger the percentage of ionic character in the bond the

more unevenly the bond electrons are shared and the more polar the bond is. The atom with the higher

electronegativity controls the bond electrons a larger percentage of the time and will be slightly negative. The

atom with the lower electronegativity is slightly positive. Bond strength also increases with percentage ionic

character. The range of polarities is as follows:

C-H

difference in electronegativity = 0.45 nonpolar covalent bond 5% ionic character

S-H

difference in electronegativity = 0.48 very slightly polar bond S is negative, H is positive

N-H

difference in electronegativity = 0.94 polar bond N is negative, H is positive

O-H

difference in electronegativity = 1.38 very polar bond O is negative, H is positive

F-H

difference in electronegativity=1.88 extremely polar bond F is negative, H is positive

Na-Cl difference in electronegativity = 2.23 ionic bond Cl is negative, Na is positive

Questions

Write a dot diagram for the HCl molecule.

Find the difference in electronegativity between the hydrogen and chlorine atoms

Is the bond nonpolar covalent, polar covalent, or ionic?

What is the percentage ionic character in the bond?

Which atom is slightly negative and which is slightly positive? Why?

Chemistry Questions Molecular Polarity