The World of Metals and Non-metals

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metallic lustre

malleability

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ductility

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rust

air, water

corrosion

galvanisation

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acidic

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Mercury

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A–(ii), B–(iii), C–(i), D–(v), E–(iv)

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Metallic lustre is the shine shown by metals. Copper, aluminium, and iron are examples of metals that show metallic lustre.

Malleability is the property by which materials can be beaten into thin sheets. Gold and silver are the most malleable metals.

Ductility is the property by which materials can be drawn into thin wires. It is important because it allows metals like copper and aluminium to be drawn into wires used in electrical fittings and musical instruments. Gold is so ductile that one gram can be drawn into a 2 km long wire.

Sonority is the property by which metals produce a ringing sound when struck. School bells and musical instruments are made of metals because of their sonority.

Cooking vessels are made of metals because metals are good conductors of heat, allowing heat to transfer efficiently to the food. Handles are made of wood or plastic because these are poor conductors of heat, preventing burns when handling hot vessels.

Rust is the brown deposit formed on iron objects when they are exposed to moist air (both air and water). The process of formation of rust is called rusting. Iron does not rust in dry air alone or in water alone — both air and water are essential.

Corrosion is the gradual deterioration of metal surfaces caused by air, water, or other substances. Examples: copper objects develop a green coating, and silver objects develop a black coating when exposed to air.

(i) Painting, (ii) Oiling, (iii) Greasing, (iv) Galvanisation (applying a protective layer of zinc on iron).

Galvanisation is the process of applying a protective layer of zinc metal on iron to prevent rusting. The zinc coating prevents air and water from coming into contact with the iron surface.

Metal oxides are basic in nature — they turn red litmus paper blue. Non-metal oxides are acidic in nature — they turn blue litmus paper red.

Sodium is a very reactive metal that reacts violently with air and moisture and may catch fire. Storing it in kerosene prevents contact with air and moisture, keeping it safe.

Phosphorus is a very reactive non-metal that catches fire when exposed to atmospheric air. It is stored under water because it does not react with water, and the water prevents contact with air.

An element is a substance that cannot be broken down into simpler substances. Presently, 118 elements are known. They are the basic building blocks of all matter. Some are naturally occurring, while others are artificially made in laboratories.

Alloys are mixtures of two or more metals, or a metal and a non-metal. They are important for daily use as utensils and tools, and for modern technologies. Example: brass is an alloy of copper and zinc.

(i) Zirconium — used in atomic energy. (ii) Titanium — used in aerospace applications.

(i) Oxygen — essential for breathing and survival. (ii) Carbon — forms the foundation of all living organisms and is a key component of proteins, fats, and carbohydrates.

Mercury is a metal that is found in a liquid state at room temperature. This property makes it suitable for use in thermometers, where it expands and contracts uniformly with temperature changes.

When magnesium burns in air, it forms magnesium oxide, which appears as white ash. Magnesium oxide is basic in nature — when dissolved in water, it turns red litmus paper blue.

When sulfur burns in air, it produces sulfur dioxide gas. Sulfur dioxide dissolves in water to form sulfurous acid, which is acidic in nature — it turns blue litmus paper red.

Recycling metals and non-metals minimises waste and contributes to sustainability. In India, many metals — especially iron and aluminium — are recycled to reduce waste and protect the environment.

Introduction: Metals are a category of elements that possess several characteristic physical properties distinguishing them from other types of materials.
Key Points:
1. Lustrous appearance — Metals have a shiny appearance called metallic lustre; copper, aluminium, and iron are lustrous examples of metals.
2. Malleable and ductile — Metals can be beaten into thin sheets (malleability) and drawn into wires (ductility); gold and silver are the most malleable and ductile.
3. Good conductors — Metals are good conductors of heat and electricity; copper and aluminium are used in cooking vessels and electrical wires respectively.
Conclusion: Metals are characterised by their lustrous appearance, malleability, ductility, and ability to conduct heat and electricity, with examples like copper, iron, and gold.

Introduction: Non-metals are substances that behave differently from metals and lack the characteristic properties that metals possess.
Key Points:
1. Non-lustrous and soft — Non-metals are usually dull in appearance and soft; sulfur and coal are non-lustrous and not as hard as metals.
2. Not malleable or ductile — Non-metals are brittle and break into pieces when beaten; they cannot be drawn into wires like metals can be.
3. Poor conductors — Non-metals are poor conductors of heat and electricity, and are not sonorous, unlike metals which produce a ringing sound.
Conclusion: Non-metals differ from metals as they are non-lustrous, soft, brittle, and poor conductors of heat and electricity, and they are not sonorous.

Introduction: Rusting of iron requires both air and water, which can be demonstrated through a simple experiment using three iron nails in different conditions.
Key Points:
1. Bottle A (dry air) — An iron nail is placed with silica gel in a sealed bottle; no rust forms because there is air but no water present.
2. Bottle B (water only) — An iron nail is fully immersed in boiled water with an oil layer; no rust forms because there is water but no air present.
3. Bottle C (air and water) — An iron nail is partially dipped in water and left open; brown rust forms because both air and water are present together.
Conclusion: The experiment proves that both air and water are essential for rusting, as rust forms only when the iron nail is exposed to both simultaneously.

Introduction: Corrosion is the gradual deterioration of metal surfaces caused by the action of air, water, or other substances over time.
Key Points:
1. Corrosion defined — Corrosion is the gradual deterioration of metal surfaces caused by exposure to air, water, or other substances in the environment.
2. Types of corrosion — Rusting of iron produces brown deposits, copper forms a green coating, and silver develops a black coating on its surface over time.
3. Prevention methods — Rusting can be prevented by painting, oiling, greasing, or applying a protective layer of zinc metal on iron through a process called galvanisation.
Conclusion: Corrosion affects different metals differently — rust on iron, green on copper, black on silver — and can be prevented by protective coatings like paint, oil, or zinc.

Introduction: Both metals and non-metals react with oxygen, but they produce oxides of different chemical nature when burned in air.
Key Points:
1. Metal + oxygen — Metals react with oxygen to form metal oxides which are basic in nature; magnesium burns to form magnesium oxide, which is basic.
2. Non-metal + oxygen — Non-metals react with oxygen to form oxides which are acidic in nature; sulfur burns to form sulfur dioxide, which is acidic.
3. Testing the oxides — Magnesium oxide turns red litmus blue (basic), while sulfur dioxide dissolved in water turns blue litmus red (acidic), confirming their different natures.
Conclusion: Metals form basic oxides while non-metals form acidic oxides when reacted with oxygen, as demonstrated by magnesium oxide and sulfur dioxide respectively.

Introduction: Some substances like sodium, potassium, and phosphorus are highly reactive with air and water, requiring special storage conditions for safety.
Key Points:
1. Sodium and potassium — Sodium and potassium react vigorously with oxygen and water, generating a lot of heat, and are stored in kerosene to prevent exposure.
2. Phosphorus — Phosphorus catches fire when exposed to atmospheric air, so it is stored in water to prevent contact with air and avoid ignition.
3. Reason for special storage — These highly reactive substances need special storage to prevent dangerous reactions with moisture and air that could cause fires or explosions.
Conclusion: Sodium and potassium are stored in kerosene, and phosphorus is stored in water, because they react dangerously with air and water if left exposed to the atmosphere.

Introduction: Elements are the basic building blocks of all matter, and metals and non-metals are two important sub-categories within the broader category of elements.
Key Points:
1. Elements defined — An element is a substance that cannot be broken down into simpler substances; presently 118 elements are known to exist.
2. Metals and non-metals as sub-categories — Metals and non-metals are sub-categories of elements, classified based on their distinct physical and chemical properties.
3. Plastic and wood — Materials like plastic, wood, glass, and rubber are not classified as metals or non-metals because they are not elements but compounds or mixtures.
Conclusion: Elements are fundamental substances that cannot be broken down further, with metals and non-metals as their sub-categories, while plastic and wood are excluded as they are not elements.

Introduction: Metals are widely used in everyday life due to their useful properties like strength, conductivity, malleability, and ductility.
Key Points:
1. Cooking vessels — Metals like copper, aluminium, and iron are used to make cooking vessels because they are good conductors of heat and are durable.
2. Electrical wiring — Copper and aluminium are used for making electrical wires because they are excellent conductors of electricity and are relatively affordable.
3. Tools and jewellery — Iron is used for making tools, spades, and axes by ironsmiths, while gold and silver are used for jewellery due to their malleability and lustre.
Conclusion: Metals are used extensively in daily life for making cooking vessels, electrical wires, tools, and jewellery, with each use depending on the metal's specific properties.

Introduction: Non-metals are equally important as metals and play essential roles in our daily life, despite lacking the physical properties of metals.
Key Points:
1. Oxygen for survival — Oxygen is a non-metal that we breathe in for respiration; without it, no living organism would be able to survive on Earth.
2. Carbon as building block — Carbon is essential as it is the building block of all life forms and is a key component of proteins, fats, and carbohydrates needed for growth.
3. Nitrogen and chlorine — Nitrogen is used in manufacturing fertilisers for plant growth, and chlorine is used in water purification to make water safe for drinking.
Conclusion: Non-metals like oxygen, carbon, nitrogen, and chlorine are essential for survival, nutrition, agriculture, and water purification, making them indispensable in everyday life.

Introduction: An electric tester circuit can be used to test whether different materials are conductors or insulators of electricity by observing if the bulb glows.
Key Points:
1. Tester setup — Design an electric circuit tester with a cell and lamp, leaving two wire ends free to touch the test materials across them.
2. Testing materials — Touch the free ends of the tester to objects like aluminium foil, iron nails, sulfur, coal, wood, and rubber one by one.
3. Conclusion drawn — Materials that make the bulb glow (aluminium, iron, copper) are metals and good conductors; those that do not (sulfur, coal, wood) are poor conductors or insulators.
Conclusion: The activity shows that all metals are good conductors of electricity while non-metals like sulfur and coal are poor conductors, confirming a clear pattern.

Introduction: Malleability is the property by which materials can be beaten into thin sheets, and it can be tested by hammering different materials.
Key Points:
1. Activity procedure — Place materials like copper, aluminium, iron nails, coal, sulfur, and wood on a hard surface and beat each with a hammer one by one.
2. Metals flatten — Copper, aluminium, and iron pieces become flat when beaten with a hammer, showing they are malleable and possess the property of malleability.
3. Non-metals break — Coal and sulfur break into pieces when beaten, showing they are brittle; wood neither flattens nor breaks, so it is neither malleable nor brittle.
Conclusion: Metals like copper, aluminium, and iron are malleable as they flatten when beaten, while non-metals like coal and sulfur are brittle and break into pieces.

Introduction: The conduction of heat can be demonstrated by comparing how a metal spoon and a wooden spoon transfer heat from hot water.
Key Points:
1. Activity setup — Fill a glass tumbler with hot water and immerse a metal spoon and a wooden spoon of similar size and thickness simultaneously.
2. Observation after time — After a few minutes, touch the upper end of each spoon; the metal spoon feels hotter than the wooden spoon.
3. Conclusion — Heat transfers through the metal spoon easily, making it a good conductor of heat, while the wooden spoon transfers heat poorly, making it a poor conductor.
Conclusion: The activity demonstrates that metals are good conductors of heat while wood is a poor conductor, explaining why cooking vessels are made of metal with wooden handles.

Introduction: Ironsmiths shape iron into useful tools by heating it and beating it with a hammer, utilising several key properties of iron metal.
Key Points:
1. Heating and shaping — The ironsmith heats an iron block in a furnace using coal until it becomes red hot, then beats it with a hammer to shape it into tools like axes.
2. Malleability of iron — Iron can be beaten into flat shapes and various forms because it is malleable, a key property that makes shaping possible.
3. Strength and hardness — Iron is hard and strong, making it suitable for making durable tools like tawas, buckets, tongs, spades, and farming implements.
Conclusion: Ironsmiths use iron's malleability, hardness, and strength to heat and hammer it into useful tools, making iron one of the most important metals for daily use.

Introduction: Rusting of iron is a significant problem in India as it damages structures and requires large amounts of money for repair and replacement every year.
Key Points:
1. Serious problem — Every year, an enormous amount of money is spent in India to replace or repair iron structures damaged due to rusting caused by moist air.
2. Prevention by coating — Rusting can be prevented by painting, oiling, or greasing iron objects to create a barrier between the iron and moist air.
3. Galvanisation — Applying a protective layer of zinc metal on iron through galvanisation prevents rusting by stopping contact with air and water.
Conclusion: Rusting of iron is a costly problem in India that can be effectively prevented by applying protective coatings like paint, oil, grease, or zinc through galvanisation.

Introduction: Metals and non-metals can be compared based on their physical properties like appearance, malleability, and conductivity, and their chemical properties with oxygen.
Key Points:
1. Physical — appearance and hardness — Metals are lustrous and hard; non-metals are non-lustrous, dull, and generally soft in nature.
2. Physical — malleability and conductivity — Metals are malleable, ductile, and good conductors of heat and electricity; non-metals are brittle and poor conductors.
3. Chemical — reaction with oxygen — Metals form basic oxides when reacted with oxygen; non-metals form acidic oxides, and non-metals generally do not react with water.
Conclusion: Metals and non-metals differ significantly in physical properties (lustre, malleability, conductivity) and chemical properties (nature of oxides formed), making them distinct categories of elements.

(a) Malleability — the property by which materials can be beaten into thin sheets and different shapes. (b) Heating iron makes it softer and easier to shape. When heated, iron becomes malleable and can be beaten into the desired shape, which hardens again on cooling. (c) Handles are made of wood because wood is a poor conductor of heat. If handles were made of metal, they would conduct heat and burn the user's hands, especially when the tool is hot.

(a) The process is called corrosion — the gradual deterioration of metal surfaces caused by air, water, or other substances. (b) Copper reacts with air and moisture to form a green coating (copper carbonate/oxide). Silver reacts with sulfur compounds in the air to form a black coating (silver sulfide). These are different types of corrosion. (c) Corrosion can be prevented by painting, oiling, greasing, or applying protective coatings to keep air and water away from the metal surface. Regular cleaning and polishing also help.

(a) The iron nail will rust only in Bottle C, where it is exposed to both air and water (moist air). No rust forms in Bottles A and B. (b) This experiment demonstrates that both air (oxygen) and water are essential for rusting. Iron does not rust in dry air alone (Bottle B) or in boiled water without air (Bottle A). Only moist air causes rusting. (c) This knowledge helps us prevent rusting by keeping iron objects away from either air or water — by painting, oiling, greasing, or galvanising (zinc coating) to create a barrier against moist air.

(a) Magnesium forms magnesium oxide (white ash). It is basic in nature. (b) Sulfur burns to produce sulfur dioxide gas. When dissolved in water, it forms sulfurous acid, which is acidic in nature. (c) For the magnesium oxide solution (basic): red litmus paper turns blue. For the sulfurous acid solution (acidic): blue litmus paper turns red. This demonstrates that metal oxides are basic and non-metal oxides are acidic.

(a) Malleability — the property by which materials can be beaten into thin sheets. Aluminium is malleable and can be rolled into thin foil. (b) Gold is both highly malleable and ductile, allowing it to be shaped into fine, intricate jewellery designs. It is also lustrous and does not corrode easily, maintaining its shine. (c) Gold and silver are chosen for jewellery because they are the most malleable and ductile metals, have a pleasing appearance (lustre), and resist corrosion and tarnishing better than common metals. They can be easily shaped into delicate designs.

(a) Sodium is a very reactive metal that reacts violently with air and moisture and may catch fire. Kerosene prevents contact with air and moisture, keeping sodium safe. It cannot be stored in water because it reacts violently with water. (b) Mercury is the only metal that is liquid at room temperature. It expands and contracts uniformly with temperature changes, making it ideal for thermometers. (c) These examples show that not all metals have the same properties. While most metals are hard and solid at room temperature, sodium is soft enough to be cut with a knife, and mercury is liquid. Metals can vary greatly in their reactivity and physical state.

(a) Copper is lustrous (shiny). Coal and wood are non-lustrous (dull). (b) Copper — will flatten (malleable). Coal — will break into pieces (brittle). Wood — will neither flatten nor break into pieces (neither malleable nor brittle). (c) Copper will conduct electricity as it is a metal and a good conductor. Coal (non-metal) and wood will not conduct electricity — they are poor conductors (insulators).

(a) Coastal areas have moist, salty air that provides both water and air (needed for rusting). The salt in the air accelerates corrosion. Inland areas have drier air, so rusting is slower. (b) Coating iron with zinc is called galvanisation. (c) Methods to prevent rusting: (i) Painting — creates a barrier between iron and air/water. (ii) Oiling and greasing — prevents contact with moist air, useful for moving parts. (iii) Galvanisation — coating with zinc, which acts as a protective barrier and prevents air and water from reaching the iron surface. These methods significantly extend the life of iron structures.

(a) Magnesium burns to form magnesium oxide, which appears as white ash: Magnesium + Oxygen → Magnesium oxide. (b) Sulfur burns to produce sulfur dioxide gas: Sulfur + Oxygen → Sulfur dioxide. (c) To confirm: Dissolve magnesium oxide in water and test with red litmus paper — it turns blue, confirming the oxide is basic. Dissolve sulfur dioxide in water and test with blue litmus paper — it turns red, confirming the oxide is acidic. Alternatively, red rose extract could be used: it turns green for the basic magnesium oxide solution and red for the acidic sulfurous acid solution.

(a) Recycling metals reduces the need for mining, conserves natural resources, saves energy, minimises waste, and protects the environment. It contributes to sustainability by reducing the environmental impact of metal production. (b) Iron — used for construction (bridges, buildings), farming tools, and machinery. Aluminium — used for packaging (cans, foil), window frames, electrical cables, and aerospace components. (c) Iron is strong, hard, and durable — suitable for construction and tools. Aluminium is lightweight, resistant to corrosion, malleable, ductile, and a good conductor — suitable for packaging, aerospace, and electrical applications.

Introduction: Metals possess several characteristic physical properties that distinguish them from other materials, though there are some notable exceptions to these general properties.
Key Points:
1. Metallic lustre — Metals have a shiny appearance called metallic lustre; copper, aluminium, and iron are lustrous, making them useful for decorative items and jewellery.
2. Malleability — Metals can be beaten into thin sheets; gold and silver are the most malleable, used as silver foil on sweets and aluminium foil for wrapping food.
3. Ductility — Metals can be drawn into wires; copper and aluminium are used for electrical wires, and gold is so ductile that one gram can make a 2-km-long wire.
4. Good conductors — Metals are good conductors of heat and electricity; copper vessels are used for cooking and copper wires for electrical conduction.
5. Exceptions — Not all metals are hard; sodium and potassium are soft enough to be cut with a knife, and mercury is a liquid metal at room temperature found in thermometers.
Conclusion: Metals are generally lustrous, malleable, ductile, and good conductors, but exceptions like soft sodium, potassium, and liquid mercury show that not all metals follow every general property.

Introduction: Non-metals are substances that differ significantly from metals in both their physical and chemical properties, with their own distinct characteristics.
Key Points:
1. Physical — appearance — Non-metals are non-lustrous and dull in appearance, unlike the shiny metallic lustre of metals like copper and iron.
2. Physical — malleability and conductivity — Non-metals are brittle and break when beaten, are not ductile, and are poor conductors of heat and electricity unlike metals.
3. Chemical — reaction with oxygen — Non-metals react with oxygen to form acidic oxides; sulfur burns to form sulfur dioxide which dissolves in water to form sulfurous acid.
4. Reaction with water — Non-metals generally do not react with water, unlike some metals like sodium that react vigorously with water.
5. Sonority — Non-metals produce a dull sound when dropped, unlike metals which produce a ringing sound due to the property of sonority.
Conclusion: Non-metals differ from metals in being non-lustrous, brittle, non-sonorous, poor conductors, forming acidic oxides, and not reacting with water, making them distinctly different elements.

Introduction: Rusting is the process of formation of a brown deposit called rust on iron objects when they are exposed to both air and water over time.
Key Points:
1. Rusting defined — When iron objects are left in the open, they develop brown deposits called rust, and the process of rust formation is called rusting.
2. Experiment — bottle A — An iron nail with silica gel in a sealed bottle has dry air but no water; no rust forms, showing water is necessary for rusting.
3. Experiment — bottle B — An iron nail fully immersed in boiled water with an oil layer has water but no air; no rust forms, showing air is necessary for rusting.
4. Experiment — bottle C — An iron nail partially dipped in water and left open has both air and water; brown rust forms, proving both are essential.
5. Prevention methods — Rusting can be prevented by painting, oiling, greasing, and galvanisation (applying a protective zinc layer on iron) to block contact with moist air.
Conclusion: The experiment with three bottles proves that both air and water are essential for rusting, and methods like painting, oiling, and galvanisation can effectively prevent it.

Introduction: Both metals and non-metals react with oxygen to form oxides, but the nature of these oxides differs significantly between the two categories.
Key Points:
1. Metal + oxygen — Metals react with oxygen to form metal oxides that are basic in nature; magnesium burns with a dazzling white flame to form magnesium oxide.
2. Testing metal oxide — When magnesium oxide is dissolved in water and tested with litmus, it turns red litmus blue, confirming the oxide is basic in nature.
3. Non-metal + oxygen — Non-metals react with oxygen to form oxides that are acidic in nature; sulfur burns to form sulfur dioxide gas.
4. Testing non-metal oxide — When sulfur dioxide is dissolved in water and tested with litmus, it turns blue litmus red, confirming the oxide is acidic.
5. Key difference — Metal oxides are basic (turn red litmus blue) while non-metal oxides are acidic (turn blue litmus red), which can be tested using acid-base indicators.
Conclusion: Metals form basic oxides and non-metals form acidic oxides when reacted with oxygen, and these oxides can be tested using litmus paper to confirm their acidic or basic nature.

Introduction: Both metals and non-metals have wide applications in everyday life, with each being suited for specific uses based on their unique properties.
Key Points:
1. Metals in cooking — Copper, aluminium, and iron are used for cooking vessels because they are good conductors of heat and are hard and durable materials.
2. Metals in wiring and jewellery — Copper is used for electrical wires due to good conductivity and low cost; gold and silver are used for jewellery due to malleability and lustre.
3. Oxygen for respiration — Oxygen, a non-metal, is essential for respiration in all living organisms; without it, no life would be possible on Earth.
4. Carbon and nitrogen — Carbon is the building block of all life forms and a component of proteins and carbohydrates; nitrogen is used in fertilisers for healthy plant growth.
5. Chlorine and iodine — Chlorine is used in water purification to make water safe, and iodine solution is applied on wounds as an antiseptic due to its germ-killing properties.
Conclusion: Metals are used for vessels, wires, and jewellery based on conductivity and malleability, while non-metals like oxygen, carbon, nitrogen, chlorine, and iodine are essential for life, agriculture, and health.

Introduction: Corrosion is the gradual deterioration of metal surfaces caused by the action of air, water, or other substances present in the environment over time.
Key Points:
1. Corrosion defined — Corrosion is the gradual deterioration of metal surfaces caused by exposure to air, water, or other substances in the surrounding environment.
2. Rusting of iron — Iron develops brown deposits called rust when exposed to moist air, which is the most common form of corrosion affecting iron objects and structures.
3. Copper and silver corrosion — Copper objects develop a green coating on their surface, and silver objects develop a black coating when exposed to air over time.
4. Why it is a problem — Corrosion weakens metal structures, and in India, an enormous amount of money is spent every year to replace or repair rusted iron structures.
5. Prevention methods — Corrosion can be prevented by painting, oiling, greasing, and galvanisation (applying a zinc coating on iron) to protect metal surfaces from air and water.
Conclusion: Corrosion causes rust on iron, green coating on copper, and black coating on silver, costing significant money for repairs, but it can be prevented by protective coatings like paint, oil, and zinc.

Introduction: Metals and non-metals can be compared across several physical and chemical properties, with some notable exceptions to the general rules.
Key Points:
1. Appearance and hardness — Metals are lustrous and hard; non-metals are non-lustrous and soft, but sodium and potassium are soft metals that can be cut with a knife.
2. Malleability and ductility — Metals are malleable and ductile; non-metals are brittle, but mercury is a metal that is liquid at room temperature, an exception.
3. Conductivity — Metals are good conductors of heat and electricity; non-metals are poor conductors, though graphite (a form of carbon) is a non-metal that conducts electricity.
4. Sonority — Metals are sonorous and produce a ringing sound; non-metals produce a dull sound when dropped, which is why school bells are made of metal.
5. Reaction with oxygen — Metals form basic oxides; non-metals form acidic oxides, as demonstrated by magnesium oxide (basic) and sulfur dioxide (acidic).
Conclusion: While metals are generally lustrous, hard, malleable, and good conductors, exceptions like soft sodium, liquid mercury, and conducting graphite show that some properties overlap between metals and non-metals.

Introduction: Metals possess several distinctive properties — malleability, ductility, sonority, and conductivity — each of which can be demonstrated through simple activities.
Key Points:
1. Malleability — Malleability is the property by which materials can be beaten into thin sheets; hammering copper and aluminium makes them flat, while coal breaks into pieces.
2. Ductility — Ductility is the property by which materials can be drawn into wires; metals like copper and gold are ductile, with one gram of gold making a 2-km-long wire.
3. Sonority — Sonority is the property by which metals produce a ringing sound; dropping a metal spoon and coin produces a ringing sound, while coal and wood produce dull sounds.
4. Conduction of heat — Heat conduction is demonstrated by immersing a metal and wooden spoon in hot water; the metal spoon gets hotter, showing metals are good heat conductors.
5. Conduction of electricity — Using an electric tester circuit, materials like aluminium and iron make the bulb glow (conductors), while sulfur and wood do not (insulators).
Conclusion: Each metal property — malleability, ductility, sonority, and conductivity — can be demonstrated through simple activities that clearly show how metals differ from non-metals.

Introduction: Yashwant and Anandi visited a local ironsmith named Sudarshan uncle to learn about how metals are shaped into useful items for daily use.
Key Points:
1. Items made by ironsmith — The ironsmith makes daily-use items like flat pans (tawas), buckets (baltis), tongs (chimtas), and farming tools like spades, axes, and rakes from iron.
2. Heating and hammering — Sudarshan heated an iron block in a furnace using coal until it became red hot, then beat it with a hammer to shape it into an axe.
3. Malleability demonstrated — Anandi observed that iron could be beaten into a flat shape, learning that this property of malleability allows metals to be shaped into various forms.
4. Uses of iron — Iron is used for making tools and utensils because it is hard, strong, and malleable, while wood is used for handles where heat insulation is needed.
5. Properties learnt — Through the visit, they learnt that metals are lustrous, hard, malleable, and can be shaped by heating and hammering, making them invaluable for crafting tools.
Conclusion: Yashwant and Anandi's visit to the ironsmith taught them about the malleability, hardness, and lustre of iron, and how these properties make metals essential for making everyday tools and utensils.

Introduction: Both metals and non-metals are essential in everyday life, and recycling metals plays an important role in sustainability and environmental conservation, especially in India.
Key Points:
1. Importance of metals — Metals are used in cooking vessels, electrical wiring, tools, jewellery, and construction due to their conductivity, strength, malleability, and durability.
2. Importance of non-metals — Non-metals like oxygen, carbon, nitrogen, chlorine, and iodine are essential for respiration, nutrition, agriculture, water purification, and medicine.
3. Special metals in technology — Some special metals like zirconium are used in atomic energy and titanium in aerospace, showing the diverse applications of metals in modern technology.
4. Recycling in India — In India, many metals especially iron and aluminium are recycled to minimise waste, conserve natural resources, and contribute to sustainability.
5. Benefits of recycling — Recycling reduces the need for mining, saves energy, reduces environmental pollution, and helps conserve finite metal resources for future generations.
Conclusion: Metals and non-metals are both vital in everyday life, and in India, recycling metals like iron and aluminium plays a crucial role in sustainability by reducing waste and conserving resources.
Chapters 5–8 (NCERT "Curiosity" Textbook)
Student: Shipan Das | Class: 7 | Subject: Science
Source: NCERT Curiosity — Textbook of Science, Grade 7 (Reprint 2026-27)
Chapters covered:
- Chapter 5: Changes Around Us: Physical and Chemical
- Chapter 6: Adolescence: A Stage of Growth and Change
- Chapter 7: Heat Transfer in Nature
- Chapter 8: Measurement of Time and Motion
Each chapter contains: Section A (55 MCQs), Section B (15 Fill in the Blanks), Section C (15 True/False), Section D (2 Match-the-Column sets, 5 pairs each), Section E (8 Assertion-Reason), Section F (20 × 2-mark), Section G (15 × 3-mark), Section H (10 × 4-mark Case/Source-based), Section I (10 × 5-mark Long Answer).