1. Chapter 17 – Properties of Matter
17.1 – Properties of Solids
Density is measurement of the compactness of a substance.
the ratio of mass and volume.
D = m/v
Units are g/mL or g/cm3

2. Density describes how tightly packed the atoms or molecules are.

3. Hardness measures a solid’s resistance to scratching
Hardness measures a solid’s resistance to scratching. Diamonds are the hardest natural substance found on Earth.

4. http://www. learner. org/jnorth/images/graphics/m/Muscle_RubberBand2
Elasticity is the measure of a solid’s ability to be stretched and then return to its original size.
Also gives objects the ability to bounce and withstand impact without breaking.
All materials have some elasticity. The most elastic are metals and rubber.

5. Brittleness measures a material’s tendency to shatter upon impact.
Brittleness is considered a hazardous property in the automobile industry.

6. The first “safety glass,” designed to reduce the brittleness of regular glass, and was discovered by accident.
In 1903, a French chemist dropped a glass flask. The flask was full of cracks, but surprisingly, the pieces did not scatter across the floor. The flask remained intact.

7. Malleability measures a solid’s ability to be pounded into thin sheets.
Ex: steel and aluminum

8. Tensile strength is a measure of how much pulling, or tension, a material can withstand before breaking.
Crucial in the manufacture of cables and girders used to support structures.

9. 17.2 – Density of Fluids
A fluid is defined as any matter that is able to flow. Both liquids and gases are a fluid.
The density of solids usually decreases as temp. increases because solids expand when heated. As the temp. of the solid increases, the volume increases.

10. Water is an exception. Ice is less dense than liquid water!
Most materials are denser in their solid phase than in their liquid phase.
Water is an exception. Ice is less dense than liquid water!

11. What would happen if solid water was denser?
Ice would sink.
Many aquatic plants could no longer grow. Animals that burrow in the mud at the bottom of ponds could not complete their life cycles.
The climate of cities along large bodies of water would become much cooler.

12. 17.3 – Buoyancy of Fluids
Buoyancy is a measure of the upward pressure a fluid exerts on an object.
In the 3rd century BC, Archimedes made an important discovery about the buoyant force.
He realized that the force exerted on an object in a liquid is equal to the weight of the fluid displaced by the object. This relationship is Archimedes’ principle.

13. Buoyancy helps explain why some objects sink and others float.
If the buoyant force is greater than its weight, the object floats.
If the buoyant force is less, then the object will sink.

14. According to Charles’ law, the volume of a gas increases with increasing temperature. The volume of a gas shrinks with decreasing temperature.

15. Pressure is the force acting on a unit area of surface.
Tire pressure is usually measured in units of psi.
The SI unit for pressure is a pascal (Pa).

16. Boyle’s law states that as the pressure of a gas increases, its volume decreases. As the pressure of a gas decreases, its volume increases.
P1V1 = P2V2

17. 17.4 – Viscosity of Fluids
Viscosity is another important property of fluids. It is a measure of the material’s resistance to flow.
Viscosity Demo

18. Viscosity is determined in large part by the shape of the molecules in a liquid. Large, bumpy molecules create more friction than small, smooth molecules

19. Remember that when energy is added to a liquid, the movement of the molecules increases.
As the temp of a liquid is raised, the viscosity of the liquid decreases.

20. Gases exhibit the opposite property
Gases exhibit the opposite property. As you raise the temperature of a gas, it becomes more resistant to flow. As a gas gets warmer, its viscosity increases.