Chemistry 0010

Matter and Energy

Topics you should learn:
1. Physical states of matter

2. Energy

3. Classification of matter

4. Chemical and physical properties of matter

Physical states of matter

After discussing the importance of measurements we now turn our attention to the two terms that form the title of this section, matter and energy.
Matter is the stuff our universe is made of. When we observe a sample of matter, it can be in any of three different physical states: solid, liquid, and gas.

For example, depending on the surrounding temperature and pressure, water can exist as:

• solid ice,
• liquid water,
• gaseous steam.

Under more restricted temperature and pressure conditions, water can coexist:

• in any combination of the above three physical states,
  • Can you think of a situation where water exists in more than one state?
• in all three physical states.

Although the three different physical states of water are quite different in physical appearance, the chemical makeup of water is the same in all three states.

Read: 3-1 - Physical states of matter (page 52)

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Energy

Unlike matter, energy is not something that you can hold in your hands. But energy is something an object has if the object is able to do work. An object can possess energy in two different ways, as kinetic energy and as potential energy.

Energy can be converted from one form to another.

kinetic energy < = > potential energy

The conversion of energy is governed by the Law of Conservation of Energy. Energy is conserved means that energy is not lost.
For example,

• Gasoline possesses potential energy that can be liberated during chemical reactions. When gasoline is burned, the gases that form have a lower potential energy than the starting material. But the decrease in potential energy cannot just disappear. It is transformed into kinetic energy (heat energy). The total kinetic energy has increased. This means that the average kinetic energy per atom must have increased. This is manifested by a rise in temperature.

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Read: 3-5 - Energy (page 62) 3-6 - Laws of Conservation (page 66)

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Classification of matter

MATTER
Substance Mixtures Elements Compounds Homogeneous Heterogeneous

Read: 3-2 - Composition and properties of matter (page 52)

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Chemical and physical properties of matter

We identify samples of matter and distinguish them from one another by their properties. We group properties into two categories:

1. Physical Properties
   • Malleability of a metal
   • Ductility of a metal
   • Hardness
   • boiling point
   • freezing point .......... etc ....

2. Chemical Properties
   • Rusting of iron
   • Burning of propane
   • Digestion of food
   • An apple turning brown ........ etc ...

A process in which a sample of matter changes its physical appearance but not its basic composition is called a physical change. In a chemical change the sample of matter undergoes a chemical reaction to change into completely different materials.

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Read: 3-4 - Properties and changes of pure substances (page 59)

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Rosamaría Fong, Instructor of Chemistry,
British Columbia Institute of Technology, Burnaby, B.C. Canada.

Send Comments to Rosamaría Fong.

All contents copyrighted © 1996
Rosamaría Fong, Instructor of Chemistry
All Rights reserved

: Last updated on June 7, 1996