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.
You will learn how metals and non-metals differ in their physical properties (how they look, feel and behave) and chemical properties (how they react with air, water and acids). Understanding these differences helps you see why we choose certain materials for certain jobs — why electric wires are made of copper, not wood, or why cooking vessels are metal, not plastic.
After studying this chapter, you should be able to identify whether a substance is a metal or non-metal, explain why metals are used for specific purposes, and predict simple reactions of metals and non-metals with common substances.
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)
Worked examples
Example 1: Identifying metals and non-metals
Riya has three samples: a shiny grey solid that conducts electricity, a yellow powder that breaks when pressed, and a reddish-brown wire. Identify which are metals and which are non-metals.
Solution:
- The shiny grey solid conducts electricity → likely a metal (could be aluminium or zinc).
- The yellow powder breaks when pressed (brittle) → likely a non-metal (could be sulphur).
- The reddish-brown wire → copper, which is a metal (can be drawn into wire, shows ductility).
Example 2: Why is copper used for electrical wires?
Arun wonders why electricians use copper wires instead of plastic threads.
Solution: Copper is a metal. Metals are good conductors of electricity. Copper allows electric current to flow through it easily. Plastic is a non-metal (made from carbon compounds) and does not conduct electricity. Therefore, copper is used for carrying current, while plastic is used as a covering to prevent shocks.
Example 3: Reaction with dilute acid
Meena drops a small piece of zinc into dilute hydrochloric acid in a test tube. What will she observe?
Solution: Zinc is a metal. Metals react with dilute acids to produce hydrogen gas. Meena will see bubbles forming around the zinc piece. If she brings a burning matchstick near the mouth of the test tube, she may hear a pop sound — this confirms hydrogen gas is released.
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.