READ: Physical and Chemical Properties

1. Physical Properties of Matter

Both of these men are skiing, but the man on the left is skiing on snow while the man on the right is skiing on sand. Snow and sand are both kinds of matter, but they have different properties. What are some ways snow and sand differ? One difference is the temperature at which they melt. Snow melts at 0°C, whereas sand melts at about 1600°C! The temperature at which something melts is its melting point. Melting point is just one of many physical properties of matter.

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2. What is Matter?

What’s the Matter?

Matter is all the “stuff” that exists in the universe. Everything you can see and touch is made of matter, including you! The only things that aren’t matter are forms of energy, such as light and sound. In science, matter is defined as anything that has mass and volume. Mass and volume measure different aspects of matter.

Mass

Mass is a measure of the amount of matter in a substance or an object. The basic SI unit for mass is the kilogram (kg), but smaller masses may be measured in grams (g). To measure mass, you would use a balance. In the lab, mass may be measured with a triple beam balance or an electronic balance, but the old-fashioned balance in the Figure below may give you a better idea of what mass is. If both sides of this balance were at the same level, it would mean that the fruit in the left pan has the same mass as the iron object in the right pan.

Mass is commonly confused with weight. The two are closely related, but they measure different things. Whereas mass measures the amount of matter in an object, weight measures the force of gravity acting on an object. The force of gravity on an object depends on its mass but also on the strength of gravity. If the strength of gravity is held constant (as it is all over Earth), then an object with a greater mass also has a greater weight.

Volume

Volume is a measure of the amount of space that a substance or an object takes up. The basic SI unit for volume is the cubic meter (m³), but smaller volumes may be measured in cm³, and liquids may be measured in liters (L) or milliliters (mL). How the volume of matter is measured depends on its state.

• The volume of a liquid is measured with a measuring container, such as a measuring cup or graduated cylinder.
• The volume of a gas depends on the volume of its container: gases expand to fill whatever space is available to them.
• The volume of a regularly shaped solid can be calculated from its dimensions. For example, the volume of a rectangular solid is the product of its length, width, and height.
• The volume of an irregularly shaped solid can be measured by the displacement method. You can read below how this method works.

Q: How could you find the volume of air in an otherwise empty room?

A: If the room has a regular shape, you could calculate its volume from its dimensions. For example, the volume of a rectangular room can be calculated with the formula:

Volume = length × width × height

If the length of the room is 5.0 meters, the width is 3.0 meters, and the height is 2.5 meters, then the volume of the room is:

Volume = 5.0 m × 3.0 m × 2.5 m = 37.5 m³

Q: What is the volume of the dinosaur in the Figure above?

A: The volume of the water alone is 4.8 mL. The volume of the water and dinosaur together is 5.6 mL. Therefore, the volume of the dinosaur alone is 5.6 mL – 4.8 mL = 0.8 mL.

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3. Mass vs. Volume

4. What are Physical Properties?

What Are Physical Properties?

Physical properties of matter are properties that can be measured or observed without matter changing to an entirely different substance. Physical properties are typically things you can detect with your senses. For example, they may be things that you can see, hear, smell, or feel.

Q: What differences between snow and sand can you detect with your senses?

A: You can see that snow and sand have a different color. You can also feel that snow is softer than sand. Both color and hardness are physical properties of matter.

Additional Physical Properties

In addition to these properties, other physical properties of matter include the state of matter. States of matter include liquid, solid, and gaseous states. For example at 20°C, coal exists as a solid and water exists as a liquid. Additional examples of physical properties include:

• odor
• boiling point
• ability to conduct heat
• ability to conduct electricity
• ability to dissolve in other substances

Some of these properties are illustrated in the Figures below, below, below, and below.

Q: The coolant that is added to a car radiator also has a lower freezing point than water. Why is this physical property useful?

A: When coolant is added to water in a car radiator, it lowers the freezing point of the water. This prevents the water in the radiator from freezing when the temperature drops below 0°C, which is the freezing point of pure water.

Q: Besides being able to conduct electricity, what other physical property of copper makes it well suited for electric wires?

A: Copper, like other metals, is ductile. This means that it can be rolled and stretched into long thin shapes such as wires.

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5. Chemical Properties

Look at the two garden trowels pictured here. Both trowels were left outside for several weeks. One tool became rusty, but the other did not. The tool that rusted is made of iron, and the other tool is made of aluminum. The ability to rust is a chemical property of iron but not aluminum.

What Are Chemical Properties?

Chemical properties are properties that can be measured or observed only when matter undergoes a change to become an entirely different kind of matter. For example, the ability of iron to rust can only be observed when iron actually rusts. When it does, it combines with oxygen to become a different substance called iron oxide. Iron is very hard and silver in color, whereas iron oxide is flakey and reddish brown. Besides the ability to rust, other chemical properties include reactivity and flammability.

Reactivity is the ability of matter to combine chemically with other substances. Some kinds of matter are extremely reactive; others are extremely unreactive. For example, the metal sodium is very reactive, even with water. When a piece of sodium is added to water, it reacts explosively. You can observe this reaction in the video below. (Caution: Don’t try this at home!) In contrast, noble gases such as helium almost never react with any other substances.

Flammability is the ability of matter to burn. When matter burns, it combines with oxygen and changes to different substances. Wood is an example of flammable matter. When wood burns, it changes to ashes, carbon dioxide, water vapor, and other gases. You can see ashes in the wood fire pictured in the Figure below. The gases are invisible.

Q: How can you tell that wood ashes are a different substance than wood?

A: Ashes have different properties than wood. For example, ashes are gray and powdery, whereas wood is brown and hard.

Q: What are some other substances that have the property of flammability?

A: Substances called fuels have the property of flammability. They include fossil fuels such as coal, natural gas, and petroleum, as well as fuels made from petroleum, such as gasoline and kerosene. Substances made of wood, such as paper and cardboard, are also flammable.

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6. Summary and Vocabulary

Summary

• Matter is all the “stuff” that exists in the universe. It has both mass and volume.
• Mass measures the amount of matter in a substance or an object. The basic SI unit for mass is the kilogram (kg).
• Volume measures the amount of space that a substance or an object takes up. The basic SI unit for volume is the cubic meter (m³).

• Physical properties of matter are properties that can be measured or observed without matter changing to an entirely different substance. Physical properties are typically things you can detect with your senses.
• Examples of physical properties of matter include melting point, color, hardness, state of matter, odor, and boiling point.

Vocabulary

• mass: Amount of matter in a substance or object.
• matter: Anything that has mass and volume.
• volume: Amount of space taken up by matter.
• physical property: Property of matter that can be measured or observed without matter changing to an entirely different substance.
• chemical property: property of matter that can be measured or observed only when matter changes to an entirely different substance.
• flammability: Ability of matter to burn.
• reactivity: Ability of a substance to combine chemically with other substances.

CK-12 Foundation, Physical Science. http://creativecommons.org/licenses/by-nc-sa/3.0/

7. Practice

Practice

Practice questions are not mandatory, but are here to help you better understand and retain lesson information.  These are not required activities, and are not part of your grade.

1. Watch the video about physical changes at the following URL. Then answer the questions below.

1. Describe an example of temperature causing a change in the size of matter.
2. How is temperature related to changes in the state of matter?

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