📚 Topic Summary
Materials around us are constantly changing. These changes can be physical, like melting ice or dissolving sugar in water, where the substance changes form but not its chemical identity. Changes can also be chemical, like burning wood or rusting iron, where a new substance is formed. Understanding these changes helps us predict and control how materials behave in different situations. Let's put your knowledge to the test!
🔬 Part A: Vocabulary
Match the following terms with their definitions:
| Term |
Definition |
| 1. Melting |
A. A substance combines with oxygen, often producing heat and light. |
| 2. Evaporation |
B. The process of a solid changing to a liquid. |
| 3. Condensation |
C. The process of a liquid changing to a gas. |
| 4. Oxidation |
D. The process of a gas changing to a liquid. |
| 5. Combustion |
E. A chemical reaction in which a substance reacts with an oxidizer to produce heat and light. |
(Answers: 1-B, 2-C, 3-D, 4-E, 5-A)
🧪 Part B: Fill in the Blanks
Complete the following paragraph using the words provided: freezing, chemical, physical, reversible, irreversible.
A ______ change alters the form of a substance but doesn't change its chemical composition. For example, ______ water turns it into ice. This is a ______ change because you can melt the ice back into water. However, burning wood is a ______ change because you cannot turn the ash back into wood. This is considered an ______ change.
(Answers: physical, freezing, reversible, chemical, irreversible)
🤔 Part C: Critical Thinking
Give an example of a change that occurs in your everyday life. Is it a reversible change? Explain why or why not.