Class 7 Science The World of Metals and Non-metals Notes

Class 7 Science The World of Metals and Non-metals Notes

Chapter 4: The World of Metals and Non-metals

Introduction

Materials around us are either metals or non-metals. Understanding their properties, reactions, and uses is important in science, technology, and daily life.

1. Properties of Metals

  • Physical Properties:
    • Lustrous (shiny)
    • Malleable (can be hammered into sheets)
    • Ductile (can be drawn into wires)
    • Good conductors of heat and electricity
    • Generally solid at room temperature (except mercury)
  • Chemical Properties:
    • React with oxygen → form oxides
    • React with water (some metals) → produce hydrogen
    • React with acids → produce hydrogen

Examples: Iron, Copper, Aluminium, Zinc

2. Properties of Non-metals

  • Physical Properties:
    • Dull in appearance
    • Brittle (break easily)
    • Poor conductors of heat and electricity (except graphite)
    • Can be solid, liquid (e.g., bromine), or gas at room temperature
  • Chemical Properties:
    • React with oxygen → form oxides
    • Generally do not react with water
    • Some react with metals to form compounds

Examples: Sulfur, Carbon, Oxygen, Chlorine

3. Reactivity of Metals

  • Metals are arranged in a reactivity series:
    Potassium > Sodium > Calcium > Magnesium > Aluminium > Zinc > Iron > Copper > Silver > Gold
  • More reactive metals react vigorously with water and acids.

4. Uses of Metals and Non-metals

SubstanceUses
IronConstruction, machines
AluminiumAircraft, utensils
CopperElectrical wires
ZincGalvanization
SulfurMatches, fertilizers
Carbon (Graphite)Pencil leads, lubricants
OxygenBreathing, medical uses

5. Key Points to Remember

  • Metals are lustrous, ductile, malleable, and good conductors; non-metals are dull, brittle, and poor conductors.
  • Metals react with acids and oxygen; some react with water.
  • Non-metals react with oxygen and metals.
  • Reactivity series helps predict chemical reactions.

Questions – The World of Metals and Non-metals

1. Very Short Answer (1 mark)

  1. Give one physical property of metals.
  2. Give one chemical property of non-metals.
  3. Name one metal that is liquid at room temperature.
  4. Give an example of a non-metal used in pencils.
  5. What is the reactivity series?
  6. Name one metal that reacts with water.
  7. Give one use of aluminium.
  8. Name one non-metal that is a gas at room temperature.
  9. What happens when metals react with acids?
  10. Give one example of a metal used in electrical wiring.

2. Multiple Choice Questions (MCQ)

  1. Which of the following is malleable?
    a) Sulfur
    b) Iron
    c) Phosphorus
    d) Carbon
  2. Which non-metal conducts electricity?
    a) Sulfur
    b) Graphite
    c) Oxygen
    d) Chlorine
  3. Copper reacts with:
    a) Water
    b) Acids
    c) Oxygen to form oxides
    d) Both b and c
  4. Which metal is used for galvanization?
    a) Iron
    b) Zinc
    c) Aluminium
    d) Copper
  5. Gold is:
    a) Very reactive
    b) Moderately reactive
    c) Least reactive
    d) Explosive

3. Fill in the Blanks

  1. Metals are good conductors of __________ and __________.
  2. Non-metals are generally __________ and __________.
  3. Mercury is a metal that is __________ at room temperature.
  4. Reactivity series helps predict the __________ of metals.
  5. Graphite is used in __________.

4. True/False Type

  1. All metals are solid at room temperature. (True/False)
  2. Aluminium is malleable and ductile. (True/False)
  3. Sulfur is a metal. (True/False)
  4. Copper is used in electrical wiring. (True/False)
  5. Metals react with acids to produce oxygen. (True/False)

5. Short Answer Questions (2–3 marks)

  1. Define metals and non-metals with two examples each.
  2. Name two physical and two chemical properties of metals.
  3. Name two physical and two chemical properties of non-metals.
  4. Give two uses of metals and two uses of non-metals.
  5. What is the significance of the reactivity series?

6. Long Answer Questions (4–5 marks)

  1. Explain the differences between metals and non-metals with a table of properties.
  2. Describe the reactivity series and give examples of highly reactive and less reactive metals.
  3. Explain the uses of metals in daily life and industry.
  4. Describe the uses of non-metals in daily life and industry.
  5. Explain why copper and aluminium are used in electrical wiring.

7. Higher-Order Thinking (HOT) & Application

  1. Why is gold used for making jewelry instead of sodium?
  2. A metal reacts vigorously with water. Predict whether it is high or low in the reactivity series.
  3. Why is graphite a good conductor while other non-metals are poor conductors?

8. Passage-Based Questions

Read the passage and answer:
Metals are lustrous, malleable, ductile, and good conductors of heat and electricity. Non-metals are dull, brittle, and poor conductors. Metals react with acids and oxygen; non-metals may react with metals and oxygen. Reactivity series ranks metals according to their chemical activity.

  1. Name two physical properties of metals.
  2. Name two properties of non-metals.
  3. What happens when metals react with acids?
  4. Give an example of a highly reactive metal and a least reactive metal.

Answer Key – The World of Metals and Non-metals

1. Very Short Answer

  1. Lustrous
  2. React with metals or oxygen
  3. Mercury
  4. Graphite
  5. Ranking of metals based on reactivity
  6. Sodium, Potassium, Calcium
  7. Aircraft, utensils
  8. Oxygen, Nitrogen, Chlorine
  9. Produce hydrogen gas
  10. Copper

2. MCQ Answers

  1. b) Iron
  2. b) Graphite
  3. d) Both b and c
  4. b) Zinc
  5. c) Least reactive

3. Fill in the Blanks

  1. heat, electricity
  2. dull, brittle
  3. liquid
  4. reactivity
  5. pencils

4. True/False

  1. False
  2. True
  3. False
  4. True
  5. False

5. Short Answer

  1. Metals: Iron, Copper; Non-metals: Sulfur, Oxygen
  2. Physical – Lustrous, Malleable; Chemical – React with oxygen, acids
  3. Physical – Dull, Brittle; Chemical – React with oxygen, metals
  4. Metals: Construction, wiring; Non-metals: Pencils, fertilizers
  5. Predicts reactions of metals with water, acids, and other metals

6. Long Answer

  1. Table of properties: Metals vs Non-metals – Physical & Chemical
  2. Highly reactive: Sodium, Potassium; Less reactive: Copper, Gold
  3. Metals: buildings, machines, wiring, utensils
  4. Non-metals: fertilizers, medicines, pencils, oxygen supply
  5. Copper and aluminium – good conductors, corrosion resistant, ductile

7. HOT & Application

  1. Sodium is highly reactive and dangerous; gold is unreactive and safe
  2. High in the reactivity series
  3. Graphite has free electrons, allowing conduction

8. Passage-Based

  1. Lustrous, malleable
  2. Dull, brittle
  3. Produce hydrogen gas
  4. Highly reactive: Sodium; Least reactive: Gold