Properties of matter

### 8th Grade Physical Science Study Guide: Properties of Matter, Buoyancy, & Density #### Key Concepts to Know for the Test (March 5th) --- ### 1. Properties of Matter Matter is anything that has mass and takes up space. It has both physical and chemical properties. #### Physical Properties: - Can be observed/measured without changing the substance. - Examples: Mass, Volume, Density, Color, Freezing Point, Boiling Point, Melting Point #### Chemical Properties: - Describe how a substance reacts with other substances. - Examples: Flammability, Reactivity with Acid, Ability to Rust --- ### 2. Mass vs. Weight - Mass = The amount of matter in an object (**measured in grams or kilograms**). - Weight = The force of gravity on an object (**measured in Newtons**). - You do not weigh the same on the Moon and Jupiter because gravity is different, but your mass stays the same! --- ### **3. Density** Density = Mass ÷ Volume - Units: g/cm³ (solids) or g/mL (liquids) - Determines whether an object sinks or floats in a fluid. - Objects with density greater than 1.0 g/mL sink in water. - Objects with density less than 1.0 g/mL float in water. - Example: A metal crate is denser than a crate of feathers because the same volume contains more mass. --- ### 4. Buoyancy - Buoyant Force = The upward force exerted by a fluid on a submerged object. - Archimedes’ Principle: An object placed in a fluid displaces a volume of fluid equal to its own volume. - Ships, submarines, and hot air balloons rely on buoyancy for movement. - Factors affecting buoyancy: - Shape (hollow boats float even if made of metal). - Density (objects with lower density than the fluid float). --- ### 5. Phase Changes & Points Matter can change from one state to another based on temperature and pressure. | Phase Change | Description | Example | |-------------|------------|---------| | Melting | Solid → Liquid | Ice melting into water | | Freezing | Liquid → Solid | Water freezing into ice | | Boiling | Liquid → Gas (at boiling point) | Water boiling into steam | | Evaporation | Liquid → Gas (below boiling point) | Puddle drying up | | Condensation | Gas → Liquid | Water droplets forming on a cold glass | | Sublimation | Solid → Gas | Dry ice turning into gas | --- ### 6. Why Understanding Density & Buoyancy Matters - Ships: Designed to float by displacing enough water (hollow hulls reduce density). - Submarines: Control buoyancy by adjusting air & water inside tanks. - Hot Air Balloons: Hot air is less dense than cold air, allowing the balloon to rise. --- ### Study Tips: ✅ Review Class Notes – Make sure you wrote down key points during class. ✅ Watch the Videos Again – Check Edpuzzle, Steve Trash Science, and the Buoyancy Video if needed. ✅ Practice Density Problems – Use the formula Density = Mass ÷ Volume to solve practice problems. ✅ Understand Real-Life Applications – Think about why density and buoyancy matter in boats, submarines, and balloons. --- ### Upcoming Deadlines & Reminders: 📌 Test on Properties of Matter – Wednesday, March 5th 📌 Boat Race Regatta – Start Collecting Cardboard! --- Let me know if you need help with anything! 🚀