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Matter makes up everything— including a portion of the GED Science subject test. Here’s a review of the basic properties of matter that you’re most likely to encounter. After going through this physical and chemical properties review for the GED, go to this post to test your knowledge with some physical science practice questions.

## What is Matter?

Matter is the material substance that everything in the universe is made of. There are three basic properties of all matter:

• Matter has mass.
• Matter takes up space.
• Matter cannot be created or destroyed, but it can change forms.

All matter is made up of atoms. Different types of atoms are called elements. Those elements can be found on the periodic table.

Need more review on these basic concepts before we move on? Check out these handy guides:

## Physical Properties of Matter

Physical properties are characteristics of matter that can be observed without changing the chemical makeup of the substance. In other words, these things do not change the kind of molecules that make up a substance.

### States of Matter

Matter comes in three different states (also called phases): solid, liquid, and gas. (Actually, if you want to be technical, scientists identify a total of five phases of matter, but you won’t see plasma or Bose-Einstein condensates showing up on the GED, so don’t worry about them.)

• Solids have densely packed, slow moving molecules. They take on a fixed shape and volume.
• Liquids are slightly less dense and faster moving than solids. They have a fixed volume but not a fixed shape. They take the shape of whatever container they’re in.
• Gases are not densely packed and their molecules move very rapidly. They don’t have a fixed shape or volume. They expand to fill whatever container they’re in.

Matter can change between phases with the addition or removal of heat. As temperatures increase, molecules speed up and eventually move into a looser configuration, changing the phase from a solid to a liquid or a liquid to a gas. Conversely, as temperatures decrease, molecules slow down and move into a more stable formation, changing gases to liquids and liquids to solids.

The phase changes are:

A change from a... ... to a... is called...
solid liquid melting
solid gassublimation
liquid solid freezing
liquidgasvaporization
gassoliddeposition
gasliquidcondensation

The temperature at which a substance changes states varies depending on the substance. Freezing point (the temperature at which a substance changes from liquid to solid) and boiling point (the temperature at which a substance changes from a liquid to a gas) are two key chemical properties. Those temperatures for water are:

FahrenheitCelsius
Freezing Point 32°F0°C
Boiling Point 212°F100°C

### Other Physical Properties

Other than its phase and phase change temperatures, matter can have other physical properties including:

• Color
• Odor
• Mass
• Volume
• Density (how tightly packed molecules are; calculated by dividing mass by volume)
• Conductivity (how well electricity can flow through the substance)

## Chemical Properties of Matter

Chemical properties of matter are those that do involve a change in a substance’s chemical composition. There are two main kinds of chemical properties— flammability and reactivity.

### Flammability

Combustion is an important chemical process. Combustion is another name for burning, and it is a chemical change that results in a substance being altered chemically.

Flammability is the chemical property that tells whether or not a substance will burn when expose to a flame.

You can also measure the heat of combustion, which is the amount of energy released when a compound undergoes complete combustion (burning) with oxygen.

### Reactivity

Reactivity is whether or not (or how easily a substance will have a chemical reaction with another substance. Some substances react very easily and others do not.

Usually when a chemical reaction occurs, you can tell by certain observable signs of reaction, such as:

• Fizzing or bubbling
• Release of heat
• Color change
• Production of light, sound, or color

Some common examples of reactivity are oxidation (reaction with oxygen), hydrolysis (reaction with water), and reaction with acid. Oxidation is the process responsible for the corrosion of metals, such as rusting.

## Physical and Chemical Changes

Along these same lines, the changes matter goes through can be classified as either physical or chemical.

Physical changes are those that do not alter the chemical makeup of the substance. The molecules are still the same type of molecules. Water can freeze, but it’s still H2O. Physical changes are also generally reversible.

Some examples of physical changes include:

• Phase changes (see chart above)
• Cutting, tearing, or breaking
• Bending

Chemical changes, on the other hand, DO change the chemical composition of the substances involved. These changes are generally not reversible.

Some examples of chemical changes include:

• Combustion
• Oxidation
• Cooking
• Decomposition
• Digestion
• Food spoiling

## Check for Understanding

Identify each of these processes as either a physical or a chemical change.

1. Baking a cake

2. Wax from a candle melting

3. A nail rusting

4. The surface of a pond freezing over

5. Paper burning

6. A piece of aluminum foil being torn

7. Milk turning sour

8. Fruit ripening

9. Dew forming on grass

10. Wood being cut into logs

1. Chemical

2. Physical

3. Chemical

4. Physical

5. Chemical

6. Physical

7. Chemical

8. Chemical

9. Physical

10. Physical

## Next Steps

Need more help with studying for the GED Science subject test? Check out our top tips for GED Science.

Ready for a Science practice test? Take a free official mini practice test from the GED Testing Service. The link to the Science test is on the right sidebar. You can also find practice tests for the other three subject tests there.