Materials Metals and Non Metals
Focused last-minute revision notes with clear concepts, exam traps, key comparisons and compact practice.
Chapter Snapshot
- Metals are generally lustrous, malleable, ductile, sonorous and good conductors.
- Non-metals are generally dull, brittle and poor conductors, but important exceptions exist.
- Metals commonly form basic oxides; many non-metals form acidic oxides.
- Many metals react with dilute acids to form a salt and hydrogen gas.
- A more reactive metal can displace a less reactive metal from its salt solution.
- Properties determine uses: copper for wires, aluminium for utensils, iron for structures, oxygen for respiration.
- No single property should be used to classify every element because exceptions exist.
What You Will Learn
- Compare physical properties of metals and non-metals
- Describe reactions with oxygen, water and acids at Class 8 level
- Explain displacement reactions
- Use properties to explain common uses
- Recognise important exceptions
Last-Minute Chapter Map
Metals and non-metals show broad property patterns, but exceptions are important.
1. Physical Properties
Metals are usually lustrous, can be beaten into sheets (malleable), drawn into wires (ductile) and produce a ringing sound when struck (sonorous). They generally conduct heat and electricity well. Non-metals are usually dull, brittle and poor conductors.
Exceptions matter: graphite is a non-metal that conducts electricity, and some metals such as sodium are soft.
2. Reaction with Oxygen
Many metals react with oxygen to form metal oxides. These oxides are often basic. Non-metals also react with oxygen; many non-metal oxides are acidic. The exact behaviour depends on the element.
3. Reaction with Water
Different metals react with water at different rates. Some react vigorously, some slowly, and some show little reaction under ordinary conditions. This variation reflects differences in reactivity.
4. Reaction with Acids
Many metals react with dilute acids to produce a salt and hydrogen gas. Non-metals generally do not release hydrogen from dilute acids in the same way. Always treat acid reactions as teacher-supervised laboratory work.
5. Displacement Reactions
A more reactive metal can displace a less reactive metal from its salt solution. For example, iron placed in copper sulphate solution can form iron sulphate and copper. The colour change and copper deposit are evidence of a chemical reaction.
6. Uses Based on Properties
Copper and aluminium are used in electrical applications because they conduct electricity. Aluminium is also light and corrosion-resistant. Iron and steel are valued for strength. Non-metals are equally important: oxygen supports respiration, nitrogen is used in fertilisers and chlorine compounds are used in water treatment.
Metals vs Non-metals
| Property | Metals | Non-metals |
|---|---|---|
| Appearance | Usually lustrous | Usually dull |
| Mechanical behaviour | Usually malleable/ductile | Usually brittle if solid |
| Sound | Often sonorous | Usually non-sonorous |
| Conductivity | Usually good | Usually poor |
| Oxides | Often basic | Many are acidic |
Exam Focus
Must Revise Before the Exam
- Malleability, ductility, sonority
- Conductivity
- Reaction with oxygen
- Reaction with dilute acids
- Displacement reaction
- Uses based on properties
- Exceptions such as graphite
Common Mistakes
Key Terms
Key Terms
Quick Revision
Quick Revision
- Metals: usually lustrous, malleable, ductile, sonorous and conductive.
- Non-metals: usually brittle and poor conductors.
- Graphite is a conducting non-metal.
- Many metal oxides are basic; many non-metal oxides acidic.
- Many metals + dilute acid → salt + hydrogen.
- More reactive metals displace less reactive metals from salt solutions.
Practice Questions
Which property means a metal can be drawn into wires?
A. Malleability
B. Ductility
C. Sonority
D. Brittleness
View Solution
Correct Answer: B. Ductility
Ductility is the ability to be drawn into wires.
Which non-metal conducts electricity?
A. Sulphur
B. Phosphorus
C. Graphite
D. Oxygen
View Solution
Correct Answer: C. Graphite
Graphite, a form of carbon, conducts electricity.
A more reactive metal can:
A. displace a less reactive metal from its salt solution
B. always dissolve in water
C. turn into a non-metal
D. stop all reactions
View Solution
Correct Answer: A. displace a less reactive metal from its salt solution
Displacement reactions depend on relative reactivity.
Which property makes copper useful for wires?
A. Brittleness
B. Electrical conductivity
C. Low melting point
D. Non-sonority
View Solution
Correct Answer: B. Electrical conductivity
Copper conducts electricity well and can be drawn into wires.
Why is aluminium commonly used for utensils?
View Solution
Aluminium conducts heat, is light, can be shaped easily and forms a protective oxide layer that helps resist corrosion.
What is a displacement reaction?
View Solution
It is a reaction in which a more reactive element replaces a less reactive element from its compound, such as iron displacing copper from copper sulphate solution.
Why can one property not be used alone to classify all elements as metals or non-metals?
View Solution
Broad patterns have exceptions. For example, graphite is a non-metal but conducts electricity, while some metals are unusually soft.
Chapter Summary
Chapter Summary
- Metals: usually lustrous, malleable, ductile, sonorous and conductive.
- Non-metals: usually brittle and poor conductors.
- Graphite is a conducting non-metal.
- Many metal oxides are basic; many non-metal oxides acidic.
- Many metals + dilute acid → salt + hydrogen.
- More reactive metals displace less reactive metals from salt solutions.