The World of Metals and Non-metals - Class 7 Science (CBSE)

Based on the 2026-27 Class 7 Science syllabus for the NCERT-aligned book Curiosity. Use these notes to understand, observe, explain, and answer in full sentences.

1. Why this chapter matters

Materials behave differently because of their properties. Metals and non-metals can be compared through observable properties and simple tests.

This chapter is not meant for rote learning. Read every idea with an example, then ask: what can I observe, test, draw, measure, or explain?

2. Core ideas

Physical properties

Many metals are lustrous, hard, malleable, ductile, sonorous, and good conductors. Many non-metals lack one or more of these properties.

Conductivity

Metals usually conduct heat and electricity well, which is why they are used in utensils, wires, and tools. Non-metals are often used as insulators.

Rusting and corrosion

Iron rusts in the presence of air and water. Rusting damages iron objects and can be slowed by painting, oiling, galvanising, or keeping dry.

3. Key points to remember

• Observation: Record what is actually seen, measured, or compared.
• Fair test: Change one factor and keep other factors the same.
• Conclusion: Use evidence to answer the question.
• Scientific vocabulary: Use precise terms from the chapter.

4. Worked examples

Example 1: Why are cooking vessels often made of metals?

Metals conduct heat well and can transfer heat to food.

Example 2: Why is sulphur not used for electrical wires?

Sulphur is a non-metal and a poor conductor of electricity.

Example 3: What conditions are needed for rusting?

Air and water are needed for iron to rust.

Example 4: Why is aluminium used in aircraft bodies?

It is light, strong enough for many uses, and resists corrosion better than iron.

5. Activity and observation

Compare iron nail, aluminium foil, copper wire, coal, sulphur, and wood for lustre, hardness, sound on tapping, and conductivity using safe classroom tests.

Write the activity in this format:

• Aim: What are you trying to find out?
• Materials: What did you use?
• Procedure: What steps did you follow?
• Observation: What did you see or measure?
• Conclusion: What scientific idea does it prove?

6. Common mistakes

• Writing only definitions without examples.
• Drawing diagrams without labels.
• Confusing observation with conclusion.
• Ignoring units in speed, time, distance, temperature, or measurement questions.
• Giving unsafe suggestions for experiments instead of classroom-safe methods.

7. Practice set

1. Define the main idea of The World of Metals and Non-metals.
2. Write two key terms from this chapter and explain them.
3. Describe one activity that proves an idea from this chapter.
4. Give one real-life application of metals.
5. Write one difference-based question from this chapter.
6. How can you make your answer more scientific?

8. Answer key

1. Define the main idea of The World of Metals and Non-metals. Answer: Materials behave differently because of their properties. Metals and non-metals can be compared through observable properties and simple tests.

2. Write two key terms from this chapter and explain them. Answer: metals and non-metals are central terms. Define each with one example from daily life.

3. Describe one activity that proves an idea from this chapter. Answer: Compare iron nail, aluminium foil, copper wire, coal, sulphur, and wood for lustre, hardness, sound on tapping, and conductivity using safe classroom tests.

4. Give one real-life application of metals. Answer: Use the chapter idea to explain a daily event, then name the observation that supports your answer.

5. Write one difference-based question from this chapter. Answer: Compare two related ideas, such as Physical properties and Conductivity, using meaning and example.

6. How can you make your answer more scientific? Answer: Use observation, correct vocabulary, labelled diagrams or tables, and a clear reason.

9. Quick revision

• Main themes: metals, non-metals, lustre, malleability, conductivity, rusting.
• Learn definitions with examples.
• Practise one diagram, table, or activity.
• Revise the worked examples.
• Write answers using cause, evidence, and conclusion.