Solubility & Intermolecular Forces

Hydrogen Bonds

• Definition: Weak forces between polar molecules containing hydrogen.

• Occurs when:

  • A slightly positive hydrogen atom (H) is attracted to a slightly negative fluorine (F), oxygen (O), or nitrogen (N).

  • Remember: Hydrogen bonding happens with "FON" (Fluorine, Oxygen, Nitrogen).

• Example: Water molecules (H₂O) hydrogen bond with each other.

What is polarity in molecules?

Polarity refers to the distribution of electric charge across a molecule, leading to partial charges due to unequal sharing of electrons.

What is the rule of solubility?

The rule of solubility states 'Like dissolves like', meaning polar molecules dissolve in polar solvents, and nonpolar molecules dissolve in nonpolar solvents.

What are hydrophilic compounds?

Hydrophilic compounds are 'water-loving' and dissolve in water because they are polar or charged, allowing them to form intermolecular bonds with water.

What are hydrophobic compounds?

Hydrophobic compounds are 'water-hating' and do not dissolve in water because they are nonpolar and cannot form bonds with water.

What are intermolecular forces (IMFs)?

Intermolecular forces are forces between molecules that determine physical properties such as boiling point, solubility, and melting point.

What are hydrogen bonds?

Hydrogen bonds are weak forces that occur between polar molecules containing hydrogen, specifically when a slightly positive hydrogen atom is attracted to a slightly negative atom like fluorine, oxygen, or nitrogen.

What is cohesion in the context of water?

Cohesion is the tendency of water molecules to attract one another, resulting in surface tension.

What is adhesion in relation to water?

Adhesion is the attraction of water molecules to other substances, enabling phenomena such as capillary action.

What are Van der Waals forces?

Van der Waals forces are weak attractions between polar molecules, including dipole-dipole interactions between slightly charged regions.

What are London Dispersion Forces (LDF)?

London Dispersion Forces are the weakest intermolecular force caused by temporary dipoles that occur when electrons shift, strongest in nonpolar molecules.

How do intermolecular forces affect physical properties?

Intermolecular forces influence boiling points, solubility, and other physical properties by determining how molecules interact.

What unique properties of water are attributed to hydrogen bonding?

The unique properties of water due to hydrogen bonding include high surface tension (cohesion), capillary action (adhesion), and its ability to act as a universal solvent.