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AP Chem



Unit 3

3.0 Unit 3 Overview: Intermolecular Forces and Properties

3 min readaugust 6, 2020

Dalia Savy

Dylan Black

From the College Board

👀 Develop Your Understanding of this unit

According to the College Board, "Transformations of matter can be observed in ways that are generally categorized as either a chemical or physical change. The shapes of the particles involved and the space between them are key factors in determining the nature of physical changes.
The properties of solids, liquids, and gases reflect the relative orderliness of the arrangement of particles in those states📚, their relative freedom of motion🏃, and the nature and strength of the interactions between them💪. There is a relationship between the macroscopic properties of solids, liquids, and gases, as well as the structure of the constituent particles of those materials on the molecular and atomic scale. In subsequent units, students will explore chemical transformations of matter."

🔎 Big Idea Questions

  • How do interactions between particles influence mixtures?
  • Why does the smell of perfume💐 only last a short time?
  • Why can you swim in water🌊 but you cannot walk through a wall🧱?
  • How are the properties of gases described?
  • How can you determine the structure and concentration of a chemical species in a mixture?

👨‍🔬 What Is Unit 3 All About?

Welcome to unit 3 of AP Chemistry! This unit is titled "Intermolecular Forces and Properties". In previous units, we've learned all about intramolecular forces, things like how atoms are built, orbitals, bonding, etc.
In this unit, we dive deep into what happens when you put a bunch of molecules (or atoms, but mostly molecules) together. We begin with a look at intermolecular forces and the states of matter, then move into gases and solutions. This unit is super exciting😆 because there are tons of real-world, out of lab experiences you have with these concepts EVERY DAY😲 and we'll come to learn all about them.
About 18-22% of the exam is about this unit! It's the largest unit on the exam but really interesting, so let's get to it🧠!

📝Key Vocabulary

Intermolecular ForcesLondon Dispersion ForcesDipole-Dipole ForcesHydrogen Bonding
PolarizabilityIon-Dipole AttractionsIon-Ion AttractionsIonic Solids
Covalent Network SolidsMolecular SolidsMetallic SolidsCrystal Lattice
DelocalizedSubstitutional AlloyInterstitial AlloySurface Tension
Capillary ActionViscosityDensityIdeal Gas Law
Combined Gas LawDalton's Law of Partial PressuresMole FractionThe Kinetic Molecular Theory
Maxwell-Boltzmann DistributionsEffusionDiffusionMolarity
Diluting SolutionsMixturesWavelengthFrequency
Planck's ConstantSolubility Electromagnetic SpectrumThe Properties of Light

🤔What you'll Learn

This unit covers a variety of different topics that include:
  • The different types of intermolecular forces
  • Strengths of each intermolecular force
  • Different types of solids and their properties
  • Different types of alloys
  • Properties of everyday objects like salt and pencil graphite
  • Different properties of liquids (surface tension, capillary action, and viscosity)
  • Relationships between volume, pressure, and temperature
  • Tons of equations about the above
  • The Kinetic Molecular Theory
  • How to interpret a Maxwell-Boltzmann Distribution
  • How to correct an ideal gas to a real gas
  • Differences between ideal gases and real gases
  • Different ways of separating a solution
  • Whether or not a substance will dissolve in a solution based on solubility rules
  • Beer-Lambert Law and Absorption

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