Polarity Notes

Polarity

Polarity relates to the periodic table and involves predicting bond types using electronegativity (AEN) values.

Predicting Bond Type from AEN Values

• Ionic: Metal to nonmetal (AEN > 1.4 or 1.5).
• Polar Covalent: Nonmetal to nonmetal or metalloid (AEN between 0.5 and 1.4 or 1.5).
• Nonpolar Covalent: (AEN between 0 and 0.4 or 0.5).

Electronegativity

Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond. The greater the difference in electronegativity between two atoms, the more polar the bond.

Polar vs Nonpolar Molecules

• Polar molecules have an uneven distribution of electron density.
• Nonpolar molecules have an even distribution of electron density.

Intermolecular Forces

Polar molecules exhibit stronger intermolecular forces compared to nonpolar molecules.

Properties Affected by Polarity

• Polar substances generally have higher melting and boiling points than nonpolar substances.

Example

Water is a polar molecule and a good solvent.

Homework

• Pg 107 #1
• Pg 108 #1, 2, 5