#AP Chemistry Unit 3: Intermolecular Forces & Properties 🧪

Hey there, future AP Chem superstar! 👋 Get ready to dive into the fascinating world of intermolecular forces, states of matter, gases, and solutions. This unit is a BIG one, making up 18-22% of your exam, but it's also super relevant to everyday life. Let's make sure you're totally prepped! 🚀

This unit is worth 18-22% of the exam, making it a high-priority area of study. Focus on understanding the relationship between intermolecular forces and the properties of matter.

#🔗 Unit Overview

• 3.1 Intermolecular Forces
• 3.2 Properties of Solids
• 3.3 Solids, Liquids, and Gases
• 3.4 Ideal Gas Law
• 3.5 Kinetic Molecular Theory
• 3.6 Deviation from Ideal Gas Law
• 3.7 Solutions and Mixtures
• 3.8 Representations of Solutions
• 3.9 Separation of Solutions and Mixtures
• 3.10 Solubility
• 3.11 Spectroscopy and the Electromagnetic Spectrum
• 3.12 Photoelectric Effect
• 3.13 Beer-Lambert Law
• Unit 3 Key Vocabulary
• Final Exam Focus
• Practice Questions

#3.1 Intermolecular Forces

Okay, let's talk about forces! But not the Star Wars kind. 😉 We're talking about intermolecular forces (IMFs), which are the attractions between molecules, not within them (that's intramolecular forces). Think of it like this: IMFs are like the friendships between people, while intramolecular forces are like the bonds within a family. 🤝

Here's a quick rundown of the major IMFs, from weakest to strongest:

• London Dispersion Forces (LDFs): The weakest IMF, present in ALL molecules. They're temporary and caused by the movement of electrons, creating temporary dipoles. Think of it like a fleeting moment of attraction. ✨
• Dipole-Dipole Interactions: Stronger than LDFs, these occur in polar molecules due to permanent dipoles. It's like a stronger, more consistent attraction between two magnets. 🧲
• Hydrogen Bonding: A special type of dipole-dipole interaction that's super strong. It only happens when H is bonded to F, O, or N. Think of it as the VIP of IMFs. 💪
• Ion-Dipole Interactions: The strongest IMF, but it only occurs in mixtures of ionic compounds and polar molecules. It's like a super strong magnet attracting a bunch of smaller magnets. 💥

#Image Courtesy of Clutch Prep

#3.2 Properties of Solids

Time to get solid! (Pun intended 😉) Solids come in two main flavors:

• Amorphous Solids: These guys are disorganized, with no repeating pattern. Think of them like a messy pile of clothes. 👕
• Crystalline Solids: These have a highly ordered, repeating structure. Think of them like a perfectly stacked set of books. 📚

In AP Chem, we're mostly focused on crystalline solids. Here are the main types:

• Metallic Solids: Held together by metallic bonds (delocalized electrons). Think of metals like copper or gold. 🪙
• Ionic Solids: Held together by ionic bonds (attraction between positive and negative ions). Think of table salt (NaCl). 🧂
• Molecular Solids: Held together by IMFs. Think of ice (H2O). 🧊
• Covalent Network Solids: Held together by covalent bonds in a continuous network. Think of diamond (C). 💎

#3.3 Solids, Liquids, and Gases

Let's zoom out and look at the three states of matter:

• Solids: Have a fixed shape and volume because their particles are tightly packed and have strong IMFs. Think of a brick. 🧱
• Liquids: Have a fixed volume but can change shape because their particles are close but can move past each other (fluidity). They also exhibit surface tension, capillary action, and viscosity. Think of water. 💧
• Gases: Have neither a fixed shape nor volume because their particles are far apart and have weak IMFs. They're compressible and can expand to fill any container. Think of air. 💨

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