Schooling · Class 7 · Science · The World of Metals and Non-metals · Chapter on a page
CBSE Class 7 · Science · NCERT Curiosity
The World of Metals and Non-metals: chapter on a page
A cut of Shishya's notes for this chapter: the first paragraph of the introduction and the key ideas, formulas and facts, common mistakes and quick revision lists, word for word. Nothing is added or reworded; the worked examples are left out (they are on the chapter page).
About the notes: Written by Shishya's AI on 26 Sept 2026 from the chapter's title and class level, in Shishya's own words — not a copy or summary of the textbook. Read the official chapter for the book's own text, activities and exercises.
This note's current text has no applied fact-check on record.
Mind map
Drawn from the same notes by a fixed rule (no AI): each label is the item's own words — its bold term, its label before a colon, a short formula as written, or its first words.
The mind map as a list
- Key ideas
- Metals are usually shiny, hard, and…
- Non-metals are usually dull, brittle…
- Metals can be beaten into thin…
- Metals generally have high melting…
- Metals react with oxygen in the air…
- Non-metals react with oxygen to form…
- Metals react with dilute acids to…
- Formulas and facts
- Lustre
- Malleability
- Ductility
- Conductor
- Insulator
- Sonorous
- Corrosion
- Watch out for
- Thinking all metals are hard
- Believing non-metals cannot be shiny
- Confusing malleability with ductility
- Assuming all metals are solid
- Thinking metals do not react with…
What this chapter is about
This chapter introduces you to two major groups of elements: metals and non-metals. You see metals every day — iron gates, aluminium pots, copper wires, gold jewellery. Non-metals are equally common — the carbon in your pencil, the oxygen you breathe, the sulphur used in crackers.
Key ideas
- Metals are usually shiny, hard, and good conductors of heat and electricity. Examples: iron, copper, aluminium, gold, silver.
- Non-metals are usually dull, brittle (break easily), and poor conductors of heat and electricity. Examples: sulphur, carbon, oxygen, nitrogen.
- Metals can be beaten into thin sheets (this property is called malleability) and drawn into wires (this property is called ductility). Non-metals cannot.
- Metals generally have high melting points, while many non-metals have low melting points. Mercury is a special metal — it is liquid at room temperature.
- Metals react with oxygen in the air to form metal oxides. For example, iron reacts with moist air to form rust (iron oxide).
- Non-metals react with oxygen to form non-metallic oxides. For example, carbon burns in air to form carbon dioxide.
- Metals react with dilute acids to release hydrogen gas. Non-metals usually do not react with dilute acids.
- Some metals like sodium and potassium are soft and can be cut with a knife. They are very reactive and stored in kerosene to keep them away from air and water.
Formulas and facts to remember
- Lustre: The shiny surface of metals when freshly cut or polished.
- Malleability: The ability of metals to be hammered into thin sheets without breaking.
- Ductility: The ability of metals to be drawn into thin wires.
- Conductor: A material that allows heat or electricity to pass through it easily. Metals are good conductors.
- Insulator: A material that does not allow heat or electricity to pass through easily. Most non-metals are insulators.
- Sonorous: Metals produce a ringing sound when struck. This property is called sonority.
- Corrosion: The slow wearing away of metals when they react with air, water or chemicals. Rusting of iron is an example.
- Metal + Oxygen → Metal oxide (example: iron + oxygen → iron oxide, which is rust)
Common mistakes
- Thinking all metals are hard → sodium and potassium are soft metals that can be cut with a knife.
- Believing non-metals cannot be shiny → iodine crystals have a shiny appearance, yet iodine is a non-metal.
- Confusing malleability with ductility → malleability means beaten into sheets; ductility means drawn into wires.
- Assuming all metals are solid → mercury is a metal but exists as a liquid at room temperature.
- Thinking metals do not react with anything → metals react with air (forming oxides), water (some metals), and acids.
Quick revision
- Metals: shiny, hard, conduct heat and electricity, malleable, ductile, sonorous.
- Non-metals: dull, brittle, poor conductors, neither malleable nor ductile.
- Rusting is the corrosion of iron when it reacts with moist air.
- Metals react with dilute acids to release hydrogen gas.
- Mercury is the only metal that is liquid at room temperature.
- Copper and aluminium are commonly used in electrical wires and cooking utensils because they conduct well.