General Chemistry 2: Intermolecular Forces

TCC Basic Education Department

• Focuses on academic excellence and community involvement

General Chemistry 2

• Taught by Ms. Nicole P. Prado, LPT, SHS Teacher

Daily Routines

• Includes prayer, class etiquette, and class attendance

Today's Foci

• Overview of the subject
• Intramolecular Forces
• Intermolecular Forces

Overview

• Intermolecular Forces and Solids
• Physical Properties of Solutions
• Thermochemistry
• Chemical Kinetics
• Chemical Thermodynamics
• Chemical Equilibrium
• Acid-Base Equilibria and Salt Equilibria
• Electrochemistry

Objectives

• Differentiate intramolecular and intermolecular forces of attraction
• Describe and differentiate the types of intermolecular forces
• Determine the intermolecular forces of attraction holding molecules together

Today's Foci (Intra and Intermolecular Forces)

Intramolecular Forces

• Forces holding atoms together within a molecule

Intermolecular Forces

• Forces existing between molecules

Types of Intramolecular Forces of Attraction

• Ionic bond: Formed by complete valence electron transfer between atoms. Metals lose electrons to become positively charged cations, and nonmetals gain electrons to become negatively charged anions.

Covalent Bond

• Formed between atoms with similar electronegativities. Atoms share electrons to achieve stable octet configuration.
  • Nonpolar covalent bond: Atoms have similar electronegativities, sharing electrons equally.
  • Polar covalent bond: Atoms have slightly different electronegativities, leading to unequal electron sharing, resulting in partial positive and negative charges.

Ionic vs. Covalent Bonds

• Ionic: Metal + Nonmetal
• Covalent: Nonmetal + Nonmetal or Metalloid + Nonmetal

Polar Covalent Bond

• Formed when atoms with slightly different electronegativities share electrons unequally

Nonpolar Covalent Bond

• Formed when atoms with similar electronegativities share electrons equally

Intermolecular Forces of Attraction

• Dipole-dipole interactions: Attractive forces between the positive end of one polar molecule and the negative end of another polar molecule.
• Ion-Dipole Interactions: Attractive force resulting from the electrostatic attraction between an ion and a neutral molecule with a dipole.
• Hydrogen Bonding: Special type of dipole-dipole interaction between hydrogen bonded to O, N, or F and slightly negative atoms of another molecule
• London Dispersion Forces: Weakest intermolecular force caused by temporary dipoles created by electron movement. Stronger as the number of electrons increases.

Strength of Intermolecular Forces

• Ion-dipole > Hydrogen Bonding > Dipole-dipole > London Dispersion

Johannes Diderik van der Waals

• Dutch scientist who studied the non-ideal behavior of real gases and attributed it to intermolecular forces.

Dipole-dipole Interactions

• Attractive forces between the positive end of one polar molecule and the negative end of another. 

Summary of Polar Molecules

• Polar molecules have partial negative and positive ends, which attract each other.

Dipole-Dipole Forces

• Much weaker than ionic or covalent bonds

Summary of Ion-Dipole Interactions

• Attractive force between an ion and a neutral polar molecule
• Common in solutions
• Positive ion attracts the partially negative end of the neutral polar molecule

Summary of Hydrogen Bonding

• Special type of dipole-dipole attraction
• Hydrogen of one molecule attracted to the electronegative atom of another (O, N, F) in another molecule.

London Dispersion Forces

• Weakest type of intermolecular force
• Exist between all molecules due to temporary dipole formation caused by electron movement
• Stronger with more electrons.

Examples of Intermolecular Interactions

• Includes various molecules and examples of different types of intermolecular forces.