Chemistry

Polar & Nonpolar Molecules

Identification:

• Polar Molecules: Uneven charge distribution (asymmetrical shape or non-canceling bond dipoles).

• Nonpolar Molecules: Even charge distribution (symmetrical shape or canceling bond dipoles).

Electronegativity:

• Definition: Atom's ability to attract shared electrons in a bond.

• Impact:

  • Large differences → Ionic bonds

  • Moderate differences → Polar covalent bonds

  • Small/no differences → Nonpolar covalent bonds

Solubility in Water:

• Polar molecules and ionic compounds dissolve in water (water's polarity interacts with them).

• Nonpolar molecules do not dissolve (lack charges to interact with water).

Properties of Water (due to Hydrogen Bonding):

• Cohesion: Water molecules stick together (surface tension).

• Adhesion: Water sticks to other surfaces.

• High Specific Heat: Resists temperature changes.

• High Heat of Vaporization: Requires significant energy to evaporate.

• Expansion upon Freezing: Ice is less dense than liquid water.

• Solvent Properties: Dissolves many polar and ionic substances.