CBSE Class 7 · Science
The World of Metals and Non-metals
Official NCERT chapter from Curiosity (book code gecu1). ExamMaster notes are original teaching at CBSE Class 7 depth.
This lesson follows the official chapter “The World of Metals and Non-metals” in Curiosity. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.
- CBSE Class 7
- Easy level
- 8 concepts
1Properties of Materials
Materials at this page are sorted by tests you can run: shine, can you beat it into a sheet or draw a wire (as demonstrated), does it ring, does it feel cold. A property is a test-result, not a brand.
“Metal” as a shop-word is not the test.
Figure. A material is a metal only if the tests say so. A steel spoon and a steel plate share the material, not the object.
How it works
- Pick one sampleThis spoon, this coal bit.
- Run one taught property-testShine, beat, wire, ring — as allowed.
- Write the resultA property, not a slogan.
2Effect of Air and Water on Metals: Iron
Iron in moist air can rust: a new brown flaky stuff. The test is the change you can see after air and water have had time, not a one-second dunk. Dry, paint, or oil can slow that job.
A wet iron nail that still looks grey after a breath is not a finished rust-case.
Figure. Iron rusts only when air and water both sit on the metal. Dry iron stays grey.
How it works
- Name iron plus air and waterThe conditions.
- Look for the brown flake after a fair waitRust as taught.
- Name a slowing job if you were shown onePaint, dry, oil.
3Effect of Air and Water on Other Metals
Other metals have their own air-and-water stories as taught: some tarnish, some stay brighter in the same time. Do not copy iron’s rust-word onto every metal.
Calling every dull coin “rust” is a borrowed word.
Figure. Copper grows a patina, silver tarnishes, aluminium keeps a thin oxide that slows further air.
How it works
- Name the metal you haveThis one, not “metal”.
- Name the change you actually saw or were shownTarnish, or little change.
- Keep iron-rust as iron’s storyOther metals get their own sentence.
4Substances that Behave Differently
Some substances do not sit neatly in the metal / non-metal poster — they behave differently on a test (as the chapter names). The heading is a warning: run the test; do not force the poster.
Forcing every sample into two buckets when the lesson named a third behaviour is the miss.
Figure. The same hit makes a metal thinner and a non-metal a powder. The test is the behaviour, not the name.
How it works
- Run the property-testThis sample.
- If it fails both posters in the way you were taught, say soBehaves differently.
- Do not invent a third metalStay with the taught exception.
5Are Non-metals Essential in Everyday Life?
Non-metals appear in daily jobs: oxygen in air you breathe, carbon in a pencil’s graphite as taught, chlorine-compounds in a treated-water story if that was the lesson. Essential means a named job, not “all non-metals are friends”.
A poison-non-metal in a later class is not this everyday-essential list.
Figure. Oxygen, nitrogen, and carbon are non-metals we live with. Essential is not the same as metallic.
How it works
- Name a non-metal you were taughtThis one.
- Name its everyday jobBreathe, write, treat — as taught.
- Keep the claim at that jobEssential-in-this-sentence.
6A definition is a test you can run
Metal / non-metal is a bundle of tests, not a shine-word. If you cannot run at least one taught test, you do not yet have the sort for this sample.
A memory that “spoons are metal” without a test is a poster.
Figure. A definition here is a test you can run. Shine alone is the trap; current and a hammer hit decide.
How it works
- Pick a testShine, beat, rust-wait, tester as taught.
- Run itThis sample.
- Then sortThe definition ran.
7Name the given before the unknown
The given is the sample and the test you were allowed. The unknown is the property or the sort. Do not relabel coal as metal because it is hard.
Hardness is not the metal-test by itself.
Figure. Name the metal and the test before you guess the coat. Iron plus air and water is a different sentence from copper in dry air.
How it works
- Name the sampleThe given.
- Name the test askedThe unknown’s door.
- Run this testGiven first.
8One worked case is enough at this class
One rust-wait or one shine-test is enough. A page of the same nail clone does not add a new air-and-water story.
Ten twins of one brown flake are still one idea.
Figure. One school case is enough: a wet iron nail rusts. Do not pile every metal into the same sentence.
How it works
- Test one sample (or one iron-wait)The case.
- A second only as a checkOptional.
- StopThis class.
Rust at this class is
- Iron’s change in moist air — a new brown flake after a fair wait
- Any dull coin
- A shine-test
Do not copy rust onto every metal.
Notes
- Mapped to the official NCERT chapter “The World of Metals and Non-metals”. Original teaching only — no textbook sentences.
- Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.
Recap
Hold these pegs from the official chapter “The World of Metals and Non-metals”. The wording is ExamMaster’s teaching, not a textbook recap.
- Properties of Materials
- Materials at this page are sorted by tests you can run: shine, can you beat it into a sheet or draw a wire (as demonstrated), does it ring, does it feel cold.
- Effect of Air and Water on Metals: Iron
- Iron in moist air can rust: a new brown flaky stuff.
- Effect of Air and Water on Other Metals
- Other metals have their own air-and-water stories as taught: some tarnish, some stay brighter in the same time.
- Substances that Behave Differently
- Some substances do not sit neatly in the metal / non-metal poster — they behave differently on a test (as the chapter names).
- Are Non-metals Essential in Everyday Life?
- Non-metals appear in daily jobs: oxygen in air you breathe, carbon in a pencil’s graphite as taught, chlorine-compounds in a treated-water story if that was the lesson.
- A definition is a test you can run
- Metal / non-metal is a bundle of tests, not a shine-word.
Practise The World of Metals and Non-metals
Reading is free and needs no account. Practice, mocks and progress live in the app.
- A 4-question practice set that ends the chapter
- 1 quick check with worked explanations
- Timed mocks scored with the real marking scheme
- Readiness tracked per topic, kept on your device