Review page for Ch. 2 Sections 3 and 4

Physical Science

Chapter 2

Review of section 3 and 4

1.             Can matter go through physical and chemical changes? Yes

2.            Give an example of a physical change: melting, wrinkling...

3.            Give an example of a chemical change: burning, rusting...

4.            Define energy: The ability to do work or cause change

5.            When matter has a lot of thermal energy, what is moving? the molecules (a molecule is a group of bonded atoms)

6.            When we measure the temperature of an object… what are we measuring?  We are measuring the overall movement of all of its molecules.  In a solid this is a vibration.

7.            What happens if we increase the thermal energy of water? The molecules move more quickly and eventually the water turns into a gas.

8.            What does the Law of the Conservation of Mass state?  Matter cannot be created or destroyed.

9.            Explain what happens to a 2 gram piece of paper when I burn it:  (where do the 2 grams of paper go?)  There is a chemical change.  The paper becomes ashes and smoke.  If you could weigh the ashes and smoke... there would still be 2 grams.

10.        Fill in the chart

	definition	example
Kinetic energy	the energy of movement	a ball rolling
Potential energy	stored energy or the energy the object possesses due to position	a ball at the top of a hill
Chemical energy	the energy stored in molecules	sugar molecules release energy when broken down
Electromagnetic energy	energy that travels through space as a wave	sound, light
Electrical energy	the energy in a flow of  electrons	the electricity in the wires that connect a battery and its light

11.     Write 2 very simple stories in which energy changes from one type to another. (such as chemical energy to kinetic energy)

The wind blows and turns a windmill.  The windmill produces electricity which powers the homes in the area.

The fireworks explode when the energy is released from the chemicals as they are exposed to heat.  The people on a hill far away can see the light waves and hear the sound waves.