Matter

2. Matter

3. Chapter Twelve: The Physical Properties of Matter • 12.1 Density • 12.2 Buoyancy • 12.3 Properties of Materials

4. Investigation 12A Density • How does density determine if an object floats or sinks?

5. 12.1 Density • Densitydescribes how much mass is in a given volume of a material.

6. 12.1 Density • Solids, liquids and gases are matter, so they all have density.

7. 12.1 Volume • Volume is the amount of space an object takes up. • The volume of a rectangular solid is found by multiplying length times width times height.

8. 12.1 Volume • Measuring the volume of liquids is easy. • Pour the liquid into a marked container called a graduated cylinderand read the volume.

9. 12.1 Displacement • You can find the volume of an irregular shape using a technique called displacement. • Find the volume of an irregularly shaped object by putting it in water and measuring the amount of water displaced.

10. 12.1 Density • The units used for density depend on whether the substance is solid or liquid. • For liquids use units of grams per milliliter (g/mL) • For solids use density in units of g/cm3 or kg/m3.

12. 12.1 Density of common materials • Density is a property of material independent of quantity or shape.

13. 12.1 Density of common materials • Liquids tend to be less dense than solids of the same material. • Water is an exception to this rule. • The density of solid water, or ice, is less than the density of liquid water.

14. 12.1 Determining Density • To find the density of a material, you need to know the mass and volume of a solid sample of the material. • Mass is measured with a balance or scale. • Use the displacement method or calculate the volume.

15. 12.1 Determining Density • When calculating volume, all of the units of length involved in the calculation must be the same.

17. 12.1 Why density varies Density changes for different substances because: • Atoms have different masses. • Atoms may be “packed” tightly or loosely.