Intermolecular Forces Quiz

Intermolecular Forces

• Intermolecular forces are forces of attraction between molecules.
• London Dispersion Forces (LDFs) are the weakest type of intermolecular force.
• LDFs are caused by temporary dipoles due to uneven electron distribution.
• LDFs are present in all molecules, but are the only intermolecular force in nonpolar molecules.
• Factors increasing LDF strength: larger molar mass, more electrons, and greater surface area. Larger surface areas offer more opportunities for interaction.
• Examples: CH4, CO2, and I2
• Dipole-dipole interactions occur between the positive end of one polar molecule and the negative end of another polar molecule.
• Dipole-dipole interactions are stronger than LDFs but weaker than hydrogen bonding.
• Examples: HCl, CH3Cl, and SO2
• Hydrogen bonding is a special type of dipole-dipole interaction.
• Hydrogen bonding occurs when hydrogen is bonded to nitrogen (N), oxygen (O), or fluorine (F).
• Hydrogen bonding creates a larger dipole moment.
• Hydrogen bonding is the strongest intermolecular force.
• Examples: H2O, NH3, and HF

Intramolecular Forces

• Intramolecular forces are forces of attraction within a molecule
• Metallic Bonds: the attraction between positive metal cations (ions) and a sea of delocalized electrons.
• Metallic bonds are present in pure metals and alloys.
• Properties of metallic bonds:
  • High conductivity due to free-moving electrons
  • Malleable and ductile
  • Variable melting points depending on the metal
  • Examples: Fe, Cu, and Al
• Ionic Bonds are electrostatic attractions between oppositely charged ions (cations and anions).
• Ionic bonds form between metals and nonmetals.
• Properties of ionic bonds:
  • High melting and boiling points
  • Conductive when molten or dissolved in water.
  • Often soluble in water
  • Examples: NaCl and MgO
• Covalent Network Bonds: atoms covalently bonded in a continuous network.
• Properties of covalent network bonds:
  • Very high melting and boiling points
  • Hard and brittle.
  • Poor conductors (no free electrons).
  • Examples: Diamond (C) and Quartz (SiO2).

Crystal Lattice Structures

• Ionic crystals: alternating positive and negative ions form a lattice.
  • Properties: High melting points, hard, brittle, and conductive when dissolved/molten
  • Example: NaCl and CaF2
• Metallic crystals: positive metal cations surrounded by a sea of delocalized electrons.
  • Properties: Good conductivity, and malleable, ductile.
  • Example: Cu and Fe
• Covalent Network Crystals: Atoms covalently bonded in a continuous network.
  • Properties: Extremely hard, very high melting points, non-conductive
  • Examples: Diamond (C), and Quartz (SiO2)
• Molecular Crystals: molecules held by intermolecular forces.
  • Properties: Lower melting points, soft, brittle, and non-conductive
  • Examples: Ice (H2O) and Sugar (C12H22O11)

Comparison of Strengths

From weakest to strongest intermolecular force

• London Dispersion Forces (weakest)
• Dipole-Dipole Interactions
• Hydrogen Bonding
• Metallic Bonds
• Ionic Bonds
• Covalent Network bonds (strongest intramolecular force)

Test your understanding of intermolecular forces, including London Dispersion Forces, dipole-dipole interactions, and hydrogen bonding. This quiz will cover key concepts, examples, and factors that influence the strength of these forces. Perfect for chemistry students looking to consolidate their knowledge.