Class 8 Science Chapter 4 🧪
Materials – Metals and Non-Metals
Complete NCERT-based notes with definitions, comparison tables, MCQs, mnemonics, Q&A, and exam tips — built for CBSE, Assam Board (SEBA) & all State Boards.
👋 Welcome, Dear Students !
Hello and a warm welcome to Jnaanangkur – The Learning Hub! Today we are going to explore one of the most interesting chapters in Class 8 Science — Metals and Non-Metals. Have you ever wondered why a spoon is made of steel and not plastic? Or why a pencil's "lead" can conduct electricity? This chapter answers exactly these everyday curiosities using real science. Grab your notebook, and let's begin this exciting journey of discovery! 🚀
📑 Quick Navigation
- Chapter Introduction & Objectives
- Chapter Summary
- Key Definitions & Terms
- Physical & Chemical Properties
- Metals vs Non-Metals Table
- Everyday Life Applications
- Important Exam Points
- Memory Tricks & Mnemonics
- NCERT Questions & Answers
- Short & Long Answer Questions
- 25+ Exam-Oriented MCQs
- Previous Year Questions
- One-Page Revision Notes
- Mind Map
- Self-Assessment Quiz
- FAQs
- Common Mistakes & Exam Tips
🌟 Chapter Introduction & Learning Objectives
Every object around us — from the iron gate of your house to the oxygen you breathe — is made of elements. Based on their properties, these elements are broadly classified into two major groups: Metals and Non-Metals. This chapter helps you understand how to identify, compare, and use this classification in daily life and in your exams.
📌 Learning Objectives
- Understand the meaning and classification of metals and non-metals
- Identify physical properties like lustre, malleability, ductility, and sonority
- Learn the chemical properties — reaction with oxygen, water, and acids
- Differentiate clearly between metals and non-metals using examples
- Connect chapter concepts with real-life applications
- Prepare effectively for CBSE, SEBA, and other State Board exams
📝 Easy-to-Understand Chapter Summary
All materials found in nature can be grouped into metals and non-metals based on certain physical and chemical properties. Metals are generally hard, shiny, and good conductors of heat and electricity — like iron, copper, aluminium, and gold. Non-metals, on the other hand, are usually dull in appearance (except a few like iodine), brittle in solid form, and poor conductors of heat and electricity — examples include sulphur, carbon, and oxygen.
The chapter explains key physical properties such as lustre (shine), malleability (ability to be hammered into sheets), ductility (ability to be drawn into wires), and sonority (producing sound when struck). It also explores chemical properties — how metals and non-metals react differently with oxygen, water, and acids to form oxides, hydroxides, and salts.
Finally, the chapter connects this classification to everyday uses: metals in utensils, wires, and machines; non-metals in fertilizers, water purification, and even the air we breathe.
🔑 Important Definitions and Key Terms
⚙️ Physical and Chemical Properties of Metals and Non-Metals
🔬 Physical Properties
⚗️ Chemical Properties
1️⃣ Reaction with Oxygen
Metals + Oxygen → Metal Oxide (Metal oxides are generally basic in nature)
Example: 2Mg + O₂ → 2MgO (Magnesium oxide)
Non-Metals + Oxygen → Non-Metal Oxide (Non-metal oxides are generally acidic in nature)
Example: C + O₂ → CO₂ (Carbon dioxide)
2️⃣ Reaction with Water
Metals like sodium and potassium react vigorously with cold water to form metal hydroxide and hydrogen gas. Metals like iron react slowly, while gold and silver do not react with water at all. Most non-metals do not react with water.
Example: 2Na + 2H₂O → 2NaOH + H₂↑
3️⃣ Reaction with Acids
Metals generally react with dilute acids to release hydrogen gas. Example: Zn + H₂SO₄ → ZnSO₄ + H₂↑. Non-metals generally do not react with dilute acids.
4️⃣ Displacement Reaction
A more reactive metal can displace a less reactive metal from its salt solution.
Example: Fe + CuSO₄ → FeSO₄ + Cu
📊 Comparison Table: Metals vs Non-Metals
| Property | Metals | Non-Metals |
|---|---|---|
| Lustre | Shiny (lustrous) | Dull (except iodine) |
| Malleability | Malleable | Brittle (non-malleable) |
| Ductility | Ductile | Non-ductile |
| Conductivity | Good conductors | Poor conductors (except graphite) |
| Sonority | Sonorous | Non-sonorous |
| Hardness | Generally hard | Generally soft (except diamond) |
| State at room temp | Mostly solid (Mercury: liquid) | Solid, liquid, or gas |
| Oxide nature | Basic oxides | Acidic oxides |
| Reaction with acid | Reacts, releases H₂ gas | Generally does not react |
| Examples | Iron, Copper, Gold, Aluminium | Sulphur, Carbon, Oxygen, Iodine |
🏠 Everyday Life Applications
| Use | Material Used | Reason |
|---|---|---|
| Cooking utensils | Aluminium, Steel | Good conductor of heat, durable |
| Electric wires | Copper | Excellent conductor of electricity, ductile |
| Jewellery | Gold, Silver | Lustrous, does not corrode easily |
| Water purification | Chlorine | Kills harmful microbes |
| Fertilizers | Nitrogen, Phosphorus | Essential nutrients for plant growth |
| Fire extinguishers | Carbon dioxide | Does not support combustion |
| Breathing (Respiration) | Oxygen | Essential for survival of living beings |
| Pencil "lead" | Graphite (Carbon) | Soft, conducts electricity unlike other non-metals |
🎯 Important Points for Examination
⚡ Must-Remember Points
- Mercury (Hg) is the only liquid metal at room temperature
- Iodine is a non-metal with a metallic lustre — an exception
- Graphite (a non-metal) conducts electricity — an exception
- Diamond (a form of carbon, non-metal) is the hardest known natural substance
- Sodium and potassium are soft metals that can be cut with a knife
- Metal oxides are basic; non-metal oxides are acidic
- Alloys are made to improve the properties of pure metals (e.g., Steel, Brass)
🧠 Memory Tricks & Mnemonics for Quick Revision
Lustrous, Malleable, Ductile, Sonorous, good Heat & electricity Conductor, generally Hard.
Mercury is a liquid metal, Iodine (non-metal) has lustre, Graphite (non-metal) conducts electricity.
Think: "Metal = Mild & Basic" and "Non-metal = Not Basic, i.e., Acidic."
📘 NCERT Questions & Answers
Q1. Name two metals which are lustrous.
Gold and Silver are two metals that show natural lustre (shine).
Q2. State whether the following statements are true or false: (a) Generally, non-metals react with acids. (b) Generally, metal oxides are acidic in nature.
(a) False — Non-metals generally do not react with acids. (b) False — Metal oxides are basic in nature, not acidic.
Q3. Sodium metal is kept immersed in kerosene oil. Why?
Sodium is a highly reactive metal that reacts vigorously with the oxygen and moisture present in air, often catching fire. To prevent this dangerous reaction, sodium is stored under kerosene oil.
Q4. Match the substances given in Column A with their uses given in Column B.
Coal – Fuel; Aluminium foil – Wrapping food; Wood – Furniture; Plastic – Bag/Toys; Copper – Electric wires (Note: students should refer to their NCERT textbook exercise for the exact matching pairs given there).
Q5. What are alloys?
Alloys are homogeneous mixtures of two or more metals, or a metal and a non-metal, mixed in fixed proportions to improve properties like strength, hardness, or resistance to rusting. Example: Steel (iron + carbon), Brass (copper + zinc).
Q6. Iron is more reactive than copper. What will happen if an iron nail is placed in a copper sulphate solution? Write the chemical equation, if any.
Iron, being more reactive, displaces copper from copper sulphate solution. The blue colour of the solution fades, and a reddish-brown coating of copper deposits on the iron nail.
Fe + CuSO₄ → FeSO₄ + Cu
Q7. Food cans are coated with tin and not with zinc because zinc is more reactive than tin. But, then why are iron tanks used to store zinc sulphate solution and not the copper sulphate solution?
Zinc is more reactive than iron, so it does not react with iron tanks, making it safe to store zinc sulphate in iron tanks. However, iron is more reactive than copper, so storing copper sulphate solution in an iron tank would cause iron to displace copper, damaging the tank and contaminating the solution.
✍️ Important Short and Long Answer Questions
Short Answer Questions (2-3 marks)
Q1. Differentiate between malleability and ductility.
Malleability is the property of a metal that allows it to be hammered into thin sheets, while ductility is the property that allows a metal to be drawn into thin wires. Both are physical properties found mainly in metals.
Q2. Why are metals good conductors of heat and electricity?
Metals contain free-moving electrons in their structure, which allow heat and electric current to pass through them easily, making metals good conductors.
Q3. Give two examples of non-metals that do not follow the general non-metal properties, and state the exception.
Graphite (a form of carbon) conducts electricity despite being a non-metal. Iodine has a shiny, metallic lustre despite being a non-metal.
Long Answer Questions (5 marks)
Q1. Describe the chemical properties of metals with examples and chemical equations.
Metals show several chemical properties:
(a) Reaction with oxygen: Metals form basic oxides — 4Na + O₂ → 2Na₂O.
(b) Reaction with water: Reactive metals like sodium react vigorously — 2Na + 2H₂O → 2NaOH + H₂.
(c) Reaction with acids: Metals release hydrogen gas — Zn + 2HCl → ZnCl₂ + H₂.
(d) Displacement reaction: A reactive metal displaces a less reactive one from its salt solution — Fe + CuSO₄ → FeSO₄ + Cu.
Q2. Compare the physical properties of metals and non-metals in detail with relevant examples.
Metals are generally lustrous, malleable, ductile, sonorous, hard, and good conductors of heat and electricity — for example, copper is ductile and used in wires. Non-metals, in contrast, are usually dull, brittle, non-sonorous, and poor conductors — for example, sulphur is brittle and breaks easily when hammered. However, exceptions exist: graphite (non-metal) conducts electricity, and iodine (non-metal) has lustre, while sodium (metal) is soft enough to be cut with a knife.
✅ 25+ Exam-Oriented MCQs with Answers
Tap "Show Answer" below each question to reveal the correct option and explanation.
1. Which of the following is the only metal that is liquid at room temperature?
Show Answer
✅ (b) Mercury — it remains liquid at normal room temperature.
2. Which non-metal has a shiny (lustrous) appearance, unlike most non-metals?
Show Answer
✅ (c) Iodine — an important exception in this chapter.
3. The property of metals that allows them to be drawn into thin wires is called:
Show Answer
✅ (b) Ductility.
4. Which of these is a non-metal that conducts electricity?
Show Answer
✅ (b) Graphite — a form of carbon, conducts electricity.
5. Metal oxides are generally:
Show Answer
✅ (b) Basic.
6. Non-metal oxides are generally:
Show Answer
✅ (a) Acidic.
7. Which metal is soft enough to be cut with a knife?
Show Answer
✅ (b) Sodium — and also potassium.
8. Which gas is released when a metal reacts with a dilute acid?
Show Answer
✅ (c) Hydrogen.
9. Sodium is stored in:
Show Answer
✅ (b) Kerosene oil — to prevent reaction with air and moisture.
10. Brass is an alloy of:
Show Answer
✅ (b) Copper and Zinc.
11. Steel is an alloy of:
Show Answer
✅ (b) Iron and Carbon.
12. Which of the following is the hardest known natural substance?
Show Answer
✅ (c) Diamond — a form of carbon (non-metal).
13. Metals that produce a ringing sound when struck are called:
Show Answer
✅ (b) Sonorous.
14. Which of these elements does NOT react with dilute acids easily?
Show Answer
✅ (c) Sulphur — a non-metal, generally unreactive with dilute acids.
15. In the reaction Fe + CuSO₄ → FeSO₄ + Cu, which metal is more reactive?
Show Answer
✅ (b) Iron — it displaces copper, showing it is more reactive.
16. Which property allows metals to be hammered into thin sheets?
Show Answer
✅ (b) Malleability.
17. Which of the following is used in fire extinguishers?
Show Answer
✅ (b) Carbon dioxide — it does not support combustion.
18. Which of these is used in making electric wires due to high conductivity and ductility?
Show Answer
✅ (b) Copper.
19. Which gas is essential for respiration in living beings?
Show Answer
✅ (b) Oxygen.
20. Tin is coated on food cans mainly because:
Show Answer
✅ (b) It is less reactive than zinc, making food safer.
21. Which of the following best describes non-metals in solid state?
Show Answer
✅ (b) Brittle.
22. Which element is essential for plant growth and used in fertilizers?
Show Answer
✅ (b) Nitrogen.
23. Which of the following metals does NOT react with cold water?
Show Answer
✅ (c) Gold — highly unreactive metal.
24. The chemical formula for magnesium oxide is:
Show Answer
✅ (b) MgO.
25. Which property is generally NOT shown by non-metals?
Show Answer
✅ (c) Ductility — non-metals cannot be drawn into wires.
26. Chlorine is commonly used for:
Show Answer
✅ (b) Water purification — it kills harmful microorganisms.
📜 Previous Year CBSE & State Board Questions
Q1. (CBSE) Explain why sodium and potassium are stored in kerosene oil. (2 marks)
Sodium and potassium are highly reactive metals that react vigorously with the oxygen and moisture present in air, sometimes catching fire spontaneously. Storing them in kerosene oil prevents direct contact with air, keeping them safe.
Q2. (State Board) Define malleability and ductility with one example each. (2 marks)
Malleability is the property of being hammered into thin sheets — gold can be beaten into very thin sheets (gold foil). Ductility is the property of being drawn into thin wires — copper is commonly drawn into electric wires.
Q3. (CBSE) Why is graphite considered an exception among non-metals? (1 mark)
Graphite is an exception because, despite being a non-metal, it conducts electricity, a property typically associated with metals.
Q4. (State Board – SEBA pattern) Write the reaction of zinc with dilute hydrochloric acid. (2 marks)
Zn + 2HCl → ZnCl₂ + H₂↑ (Zinc reacts with dilute hydrochloric acid to form zinc chloride and release hydrogen gas.)
📄 One-Page Revision Notes
⚡ Chapter 4 at a Glance
- Metals: Lustrous, malleable, ductile, sonorous, good conductors, generally hard, mostly solid (Hg is liquid).
- Non-Metals: Dull (except I₂), brittle, non-ductile, poor conductors (except graphite), generally soft (except diamond).
- Metal + Oxygen → Basic Oxide | Non-Metal + Oxygen → Acidic Oxide
- Reactive metals (Na, K) react vigorously with water; Au, Ag do not react.
- Metal + Dilute Acid → Salt + H₂ gas (Non-metals generally don't react with acids)
- Displacement: More reactive metal displaces less reactive metal from its salt solution.
- Alloys: Steel (Fe+C), Brass (Cu+Zn), Bronze (Cu+Sn) — improve metal properties.
- Key Exceptions: Mercury (liquid metal), Iodine (lustrous non-metal), Graphite (conducting non-metal), Diamond (hardest non-metal).
🗺️ Mind Map
🧪 Self-Assessment Quiz
Test yourself! Answer these quickly without scrolling back up, then check using the MCQ section above for similar concepts:
- Name one metal that is a poor conductor... wait, is there one? Think again! (Trick question — all metals are good conductors!)
- Which non-metal is used in pencils and conducts electricity?
- What do you call a mixture of two metals?
- Which gas is released when zinc reacts with hydrochloric acid?
- True or False: Non-metal oxides are basic in nature.
Answers: 1) Trick — all metals conduct well; 2) Graphite; 3) Alloy; 4) Hydrogen; 5) False (they are acidic)
❓ Frequently Asked Questions (FAQs)
Q1. What is the main difference between metals and non-metals?
Metals are generally lustrous, malleable, ductile, and good conductors of heat and electricity, while non-metals are usually dull, brittle, and poor conductors.
Q2. Why is mercury considered an exception among metals?
Mercury is the only metal that exists in liquid state at room temperature, unlike most other metals which are solid.
Q3. Is graphite a metal or non-metal?
Graphite is a non-metal (a form of carbon), but it is an exception because it conducts electricity, unlike most non-metals.
Q4. What are alloys and why are they used?
Alloys are mixtures of two or more metals (or a metal and non-metal) created to enhance properties like strength, hardness, and resistance to corrosion. Steel and brass are common examples.
Q5. Why is sodium stored in kerosene oil?
Because sodium reacts vigorously with oxygen and moisture in air, kerosene oil prevents this dangerous reaction by isolating it from air.
Q6. Are all non-metals bad conductors of electricity?
Mostly, yes — except graphite, which is a notable exception that conducts electricity well.
⚠️ Common Student Mistakes & Exam Tips
✅ Fix: Always mention "except graphite" when writing about non-metal conductivity to score full marks.
✅ Fix: Remember: "M for Malleable, M for hammered into sheets" and "D for Ductile, D for drawn into wires."
✅ Fix: Metal oxides = Basic. Non-metal oxides = Acidic. Practice this twice before exams.
✅ Fix: Always double-check that atoms are balanced on both sides before submitting your answer.
🌟 Final Words from Jnaanangkur
Science is not just about memorizing facts — it's about observing the world around you with curiosity. The next time you pick up a spoon, touch a copper wire, or sharpen your pencil, pause for a moment and think about the properties of metals and non-metals you just learned. That little observation is the true spirit of science!
Keep learning, keep questioning, and keep growing — your strong foundation in Science starts right here at Jnaanangkur – The Learning Hub! 🚀📚
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