9.3. Polarity in Chemical Bonds http://www.ck12.org
9.3 Polarity in Chemical Bonds
Lesson Objectives
- Understand the concept of polarity.
- Define electronegativity.
- Determine the polarity of a chemical bond using the electronegativity chart.
- Distinguish between nonpolar covalent, polar covalent, and ionic bonds in terms of electron sharing.
Lesson Vocabulary
- polarity: A property of molecules in which one or more atoms possess either a partial positive or a partial
negative charge. - electronegativity: The ability to attract shared electrons.
- nonpolar covalent bond: Exists only between two identical atoms.
- polar covalent bond: Exists when the electrons are still shared (the bond is covalent), but the bond is
significantly polarized.
Check Your Understanding
Recalling Prior Knowledge
- What are covalent bonds?
Introduction
We have learned that covalently bonded molecules share valence electrons in order for atoms to fill their valence
shells. However, sometimes one of the atoms has a greater attraction for electrons than another, resulting in an
unequal sharing of electrons. This results in molecularpolarity.
Electronegativity
When two atoms of different elements come together to form a bond, the atoms generally do not attract the
shared electrons with the same amount of pull. The ability to attract shared electrons is a property known as
electronegativity. The higher the electronegativity value, the more pull is exerted by that element. Electronegativity
values for various elements are found inFigure9.12.