Name: ______
Date: ______7th Grade Science- Ms. Lyons
Circle your group: F ~ G ~H
Physical and Chemical Changes Reading
Directions: Answer all questions in complete sentences in your own words.
Matter can be changed in many ways.In a physical change, a substance changes shape or size, but the material from which it is made remains the same. Think of a piece of aluminum foil. You can tear it, fold it, crumple it, or roll it into a tube. Each change changes the shape of the foil, but it does not change what the foil is made of. It is still aluminum. It is the same substance it was before you made any of these changes. Other examples of physical changes include ripping, tearing, folding, freezing, melting, condensation, boiling and evaporation.
- What is the definition of a physical change IN YOUR OWN WORDS?
A physical change is
- How do you know that tearing a piece of aluminum foil is a physical change?
Tearing aluminum foil is a physical change because
- What are two examples of physical changes?
Two examples of physical changes are
A chemical change is a change where a new material is made. When you light a match, the match changes from one material to another. Before the match is lit, it is made of the element sulfur and is red in color. Once it is lit, it changes to sulfur dioxide and becomes grey in color. There are several clues that this chemical change has occurred such as the strong smell of sulfur dioxide, smoke, and a color change. Other examples of chemical changes include metal rusting, glow sticks lighting up after being bent, and cakes baking.
- What is the definition of a chemical change IN YOUR OWN WORDS?
A chemical change is
- What is a match made of before it is lit? What is a match made up of after it is lit?
It is made up of
- How do you know that lighting a match is a chemical change?
Lighting a match is a chemical change because
8. What are two examples of chemical changes?
Two examples of chemical changes are
9. What is the main point of the article?
The main point of the article is ______
______
How do you know that you have a new substance? Is it just because it looks different? You could put a salad in a blender and it would look different, but a chemical change would not have occurred. You still have lettuce, carrots, and any other vegetables that were there to begin with. You can look for signs when evaluating whether you have a new substance as a result of a chemical change. When a cake bakes, gas bubbles form and grow within the ingredients. Bubbles are a sign that a chemical change has taken place. When you look closely at a piece of cake, you can see the air holes left from the bubbles.
- What is one clue that a chemical change has taken place that you can see when you make a birthday cake?
One clue that a chemical change has taken place is because
______
One other way to determine whether a physical change or a chemical change has occurred is to decide whether or not you can reverse the change by simple physical means. Physical changes usually can be reversed easily. For example, melted butter can become solid again if it is placed in the refrigerator. A figure made of modeling clay, can be smashed to fit into a container. However, chemical changes can’t be reversed using physical means. For example, the ashes in a fireplace cannot be put back together to make the logs to start with.
- What is another way to determine whether a chemical or physical change has taken place?
Another way to determine whether a chemical or physical change takes place is by
- What is the main point of the article?
The main point of this article is