The World of Metals and Non-metals

Materials ko unki properties ke basis par metals aur non-metals mein classify kiya jaata hai. Yeh classification unki physical aur chemical properties par depend karta hai.

Physical Properties (भौतिक गुण)

• Lustre (चमक):
• Metals: Generally lustrous (चamakdaar) hote hain, matlab unki surface par ek khas chamak hoti hai, jise metallic lustre kehte hain. Example: Gold, Silver, Copper.
• Non-metals: Usually non-lustrous (pheeke) hote hain. Example: Coal, Sulfur, Wood.
• Exception: Iodine ek non-metal hai jo lustrous hota hai.

• Hardness (कठोरता):
• Metals: Generally hard (kathor) hote hain. Example: Iron, Copper, Aluminium.
• Non-metals: Usually soft (naram) hote hain. Example: Coal, Sulfur.
• Exceptions:
• Metals: Sodium (Na) aur Potassium (K) itne soft hote hain ki unhe knife se cut kiya ja sakta hai. Mercury (Hg) room temperature par liquid state mein hota hai.
• Non-metals: Diamond (carbon ka allotrope) sabse hard natural substance hai.

• State (अवस्था):
• Metals: Mostly solid hote hain room temperature par.
• Non-metals: Solid, liquid, ya gas ho sakte hain room temperature par. Example: Sulfur (solid), Bromine (liquid), Oxygen (gas).

Activity 4.1 Summary:

• Jab iron nail, copper piece, aluminium piece ko hammer se beat kiya jaata hai, toh woh flatten ho jaate hain.
• Lekin coal piece aur sulfur lump break into pieces ho jaate hain.
• Yeh activity malleability ki property ko demonstrate karti hai. (Aage detail mein padhenge)

Holistic Lens: Iron ka Impact

• Ancient India mein Harappans copper aur gold use karte the, lekin iron ka use baad mein aaya.
• Iron ke use se civilization mein bahut progress hui, especially agriculture mein stronger ploughs aur tools banane se.
• Question: Copper iron se pehle kyun discover hua? Copper earth's crust mein free state mein milta hai, jabki iron ores se extract karna padta hai, jiske liye high temperature ki zaroorat hoti hai.

[IMAGE: an_ironsmith_at_work_fig41] ironsmith ko kaam karte hue dekho.

Malleability (आघातवर्धनीयता)

• Yeh metals ki woh property hai jisse unhe hammer karke thin sheets (patli chaadaron) mein convert kiya ja sakta hai.
• Most metals malleable hote hain. Example: Aluminium foil for food wrapping, silver foil on sweets.
• Gold aur Silver sabse zyada malleable metals hain.
• Non-metals (jaise coal, sulfur) malleable nahi hote, woh brittle hote hain, matlab hammer karne par pieces mein toot jaate hain.

Ductility (तन्यता)

• Yeh metals ki woh property hai jisse unhe thin wires (patle taaron) mein draw kiya ja sakta hai.
• Most metals ductile hote hain. Example: Copper aur Aluminium wires electrical fittings mein use hote hain. Gold aur silver se ornaments bante hain.
• Gold sabse zyada ductile metal hai (1 gram gold se 2 km lamba wire ban sakta hai!).
• Non-metals ductile nahi hote. Coal ya sulfur ke wires nahi ban sakte.
• Dive Deeper: Steel (iron + carbon ka mixture) wires heavy loads support karte hain, isliye suspension bridges aur cranes mein use hote hain.

Sonority (ध्वनि)

• Yeh metals ki woh property hai jisse woh ringing sound (ghanti jaisi awaaz) produce karte hain jab unhe hit kiya jaata hai.
• Metals ko sonorous kaha jaata hai. Example: School bell, metal spoons, coins.
• Non-metals (jaise wood, coal) dull sound produce karte hain, woh sonorous nahi hote.
• Activity 4.2: Metal spoon/coin ko drop karne par ringing sound aati hai, jabki coal/wood se dull sound.

[IMAGE: tea_strainer_an_example_of_ductility_figmage_cbse_g7] ductility ka example.

Conduction of Heat (ऊष्मा चालन)

• Activity 4.3: Hot water mein metal spoon aur wooden spoon daalne par metal spoon garam ho jaata hai, jabki wooden spoon nahi.
• Iska matlab hai ki heat metal spoon se transfer hui, lekin wooden spoon se nahi.
• Conductors (चालक): Woh materials jo heat ko easily transfer karte hain. Metals good conductors of heat hote hain. Example: Cooking vessels metals (copper, aluminium) se bante hain.
• Insulators (कुचालक): Woh materials jo heat ko poorly transfer karte hain. Non-metals (jaise wood) poor conductors of heat hote hain. Example: Cooking vessels ke handles wood ya plastic se bante hain.

Conduction of Electricity (विद्युत चालन)

• Activity 4.4 (Electric Tester):
• Jab aluminium, iron, copper jaise materials ko tester circuit mein use karte hain, toh bulb glow karta hai.
• Jab sulfur, coal, wood jaise materials ko use karte hain, toh bulb glow nahi karta.
• Good Conductors of Electricity: Woh materials jo electricity ko easily flow hone dete hain. Metals good conductors hote hain. Example: Copper aur aluminium wires electrical wiring mein use hote hain.
• Poor Conductors of Electricity (Insulators): Woh materials jo electricity ko flow nahi hone dete. Non-metals poor conductors hote hain. Example: Rubber, plastic, wood.
• Exception: Graphite (carbon ka allotrope, non-metal) electricity ka good conductor hai.
• Reason: Electricians rubber gloves aur shoes pehente hain kyunki rubber poor conductor of electricity hai, jo unhe electric shock se bachata hai.

Summary of Physical Properties:

Metals generally:

• Hard (except Na, K, Hg)
• Lustrous
• Malleable
• Ductile
• Sonorous
• Good conductors of heat and electricity

Non-metals generally:

• Soft (except Diamond)
• Non-lustrous (except Iodine)
• Brittle
• Non-ductile
• Non-sonorous
• Poor conductors of heat and electricity (except Graphite)

[IMAGE: heat_conduction_in_different_materials_fig43] heat conduction ka example.

Metals air aur water ke saath react karte hain, jisse unki properties change ho sakti hain.

Rusting of Iron (लोहे में जंग लगना)

• Jab iron objects ko moist air (nam hawa) mein rakha jaata hai, toh unpar brownish-red flaky substance deposit ho jaata hai, jise rust (जंग) kehte hain.
• Rusting ek slow process hai jisme iron oxygen aur water vapor ke saath react karta hai.
• Conditions for Rusting: Rusting ke liye dono oxygen (air) aur water (moisture) ka hona zaroori hai.

Activity 4.5: Conditions for Rusting

• Bottle A (Dry Air): Iron nail + Silica gel (moisture absorber). No rust.
• Bottle B (Boiled Water + Oil): Iron nail + Boiled water (dissolved oxygen removed) + Oil layer (air ko water mein dissolve hone se rokta hai). No rust.
• Bottle C (Air + Water): Iron nail + Water (partially dipped) + Open to air. Rust forms.
• Conclusion: Rusting ke liye air (oxygen) aur water (moisture) dono ki presence essential hai.

Corrosion (संक्षारण)

• Corrosion: Metals ka gradual deterioration (dheere-dheere kharab hona) air, water, ya other substances ke contact mein aane se. Rusting iron ka corrosion hai.
• Examples of Corrosion:
• Iron par brown rust.
• Copper objects par greenish coating (copper carbonate).
• Silver objects par black coating (silver sulfide).
• Harmful Effects: Rusting se iron structures (bridges, railings, vehicles) ko bahut damage hota hai, jisse economic loss hota hai.

Prevention of Rusting (जंग से बचाव)

Rusting ko rokne ke liye kuch methods:

1. Painting: Iron objects par paint ki layer lagana.
2. Oiling/Greasing: Oil ya grease ki layer lagana.
3. Galvanisation (गैल्वनीकरण): Iron par zinc metal ki thin layer deposit karna. Zinc iron se zyada reactive hota hai aur pehle corrode hota hai, iron ko bachata hai.
4. Chromium Plating: Chromium ki layer lagana (shiny look bhi deta hai).
5. Alloying: Iron ko dusre metals ya non-metals ke saath mix karke alloy banana (jaise stainless steel).

Fascinating Facts: Iron Pillar of Delhi

• Delhi ka Iron Pillar 1600 saal se bhi zyada purana hai.
• Itna purana hone ke bawajood, ispar na ke barabar rust hai.
• Yeh ancient Indian metallurgists ki advanced skills ko dikhata hai, jinhone isse rust-resistant banaya.

[IMAGE: conditions_for_rusting_of_iron_fig44] rusting ke conditions.

Reaction with Oxygen (Air)

• Metals oxygen ke saath react karke metal oxides banate hain.
• Metal + Oxygen $\rightarrow$ Metal Oxide
• Activity 4.6 (Burning Magnesium Ribbon):
• Magnesium ribbon ko air mein burn karne par dazzling white flame ke saath jalta hai aur white powder (Magnesium Oxide) banta hai.
• Reaction: $2Mg (s) + O_2 (g) \rightarrow 2MgO (s)$
• Magnesium oxide ko water mein dissolve karne par Magnesium Hydroxide banta hai.
• $MgO (s) + H_2O (l) \rightarrow Mg(OH)_2 (aq)$
• Magnesium hydroxide solution red litmus ko blue kar deta hai, iska matlab hai ki yeh basic (क्षारीय) nature ka hai.
• Conclusion: Generally, metal oxides basic nature ke hote hain.
• Sodium (Na): Sodium metal highly reactive hota hai. Yeh air (oxygen) aur water ke saath vigorously react karta hai aur bahut heat produce karta hai, jisse fire lag sakti hai.
• Isliye, sodium ko kerosene oil mein store kiya jaata hai, taaki uska contact air aur moisture se na ho.
• Sodium oxide bhi basic nature ka hoga.

Reaction with Water

• Metals water ke saath react karke metal hydroxides ya metal oxides aur hydrogen gas banate hain.
• Metal + Water $\rightarrow$ Metal Hydroxide/Oxide + Hydrogen gas
• Different metals ki water ke saath reactivity different hoti hai:
• Sodium (Na) aur Potassium (K): Cold water ke saath vigorously react karte hain, heat produce karte hain aur hydrogen gas fire catch kar leti hai.
• Calcium (Ca): Cold water ke saath react karta hai, lekin less vigorously. Hydrogen gas bubbles calcium ki surface par stick ho jaati hain, jisse calcium float karta hai.
• Magnesium (Mg): Cold water ke saath react nahi karta, lekin hot water ke saath react karke magnesium hydroxide aur hydrogen gas banata hai.
• Aluminium (Al), Iron (Fe), Zinc (Zn): Cold ya hot water ke saath react nahi karte, lekin steam ke saath react karke metal oxide aur hydrogen gas banate hain.
• Lead (Pb), Copper (Cu), Silver (Ag), Gold (Au): Water (cold, hot, ya steam) ke saath bilkul react nahi karte.

[IMAGE: burning_magnesium_ribbon_fig45] magnesium ribbon ko jalate hue.

Reaction with Oxygen (Air)

• Non-metals oxygen ke saath react karke non-metal oxides banate hain.
• Non-metal + Oxygen $\rightarrow$ Non-metal Oxide
• Activity 4.7 (Burning Sulfur):
• Sulfur ko air mein burn karne par sulfur dioxide gas banti hai.
• Reaction: $S (s) + O_2 (g) \rightarrow SO_2 (g)$
• Sulfur dioxide gas ko water mein dissolve karne par sulfurous acid banta hai.
• $SO_2 (g) + H_2O (l) \rightarrow H_2SO_3 (aq)$
• Sulfurous acid solution blue litmus ko red kar deta hai, iska matlab hai ki yeh acidic (अम्लीय) nature ka hai.
• Conclusion: Generally, non-metal oxides acidic nature ke hote hain.

Reaction with Water

• Generally, non-metals water ke saath react nahi karte hain.
• Activity 4.8: Sulfur powder ko water mein daalne par koi reaction nahi hoti.
• Phosphorus (P): Ek highly reactive non-metal hai. Yeh air mein expose hone par fire catch kar leta hai.
• Isliye, phosphorus ko water mein store kiya jaata hai, taaki uska contact atmospheric oxygen se na ho.

Summary of Chemical Properties:

• Metals:
• Oxygen se react karke basic oxides banate hain.
• Water se react karte hain (reactivity varies).
• Non-metals:
• Oxygen se react karke acidic oxides banate hain.
• Generally water se react nahi karte hain.

Elements (तत्व)

• Metals aur non-metals elements ke sub-categories hain.
• Element: Ek substance jise simpler substances mein break nahi kiya ja sakta chemical means se.
• Currently, 118 elements known hain. Yeh matter ke basic building blocks hain.

[IMAGE: burning_of_sulfur_fig47c] sulfur ko jalate hue.

Metals aur non-metals dono hamari daily life aur modern technology mein bahut important hain.

Uses of Metals (धातुओं के उपयोग)

• Utensils (बर्तन) aur Tools (औजार): Iron, Aluminium, Copper ka use cooking utensils, farming tools, construction materials banane mein hota hai.
• Electrical Wiring: Copper aur Aluminium wires electrical circuits mein use hote hain kyunki yeh good conductors of electricity hain.
• Jewellery (आभूषण): Gold, Silver, Platinum apni lustre aur malleability/ductility ke karan jewellery mein use hote hain.
• Machinery aur Vehicles: Iron, Steel (alloy), Aluminium ka use cars, aeroplanes, trains, aur heavy machinery banane mein hota hai.
• Specialised Uses:
• Atomic Energy: Zirconium.
• Aerospace: Titanium.
• Recycling: India mein iron aur aluminium jaise metals ko recycle kiya jaata hai waste kam karne aur sustainability promote karne ke liye.

Uses of Non-metals (अधातुओं के उपयोग)

• Oxygen (O):
• Respiration (साँस लेने) ke liye essential hai (human aur animals).
• Combustion (jalne) ke liye zaroori hai.
• Hospitals mein patients ko diya jaata hai.
• Carbon (C):
• Sabhi living organisms ka building block hai (proteins, fats, carbohydrates).
• Fuel (coal, petroleum) mein present hota hai.
• Diamond (jewellery, cutting tools) aur Graphite (pencil leads, lubricants) carbon ke forms hain.
• Nitrogen (N):
• Fertilisers (उर्वरक) banane mein use hota hai, jo plants ki growth ke liye essential hai.
• Chemicals banane mein use hota hai.
• Food packaging mein use hota hai (inert atmosphere provide karne ke liye).
• Chlorine (Cl):
• Water purification (paani saaf karne) mein use hota hai (germs kill karta hai).
• Bleaching agents aur disinfectants mein use hota hai.
• Iodine (I):
• Antiseptic ke roop mein wounds par apply kiya jaata hai (Tincture of Iodine).
• Thyroid gland ke proper functioning ke liye essential hai.
• Sulfur (S):
• Sulfuric acid banane mein use hota hai (industrial chemical).
• Fungicides aur gunpowder mein use hota hai.

Alloys (मिश्र धातु)

• Alloy: Two or more metals, ya ek metal aur ek non-metal ka homogeneous mixture. Alloys generally pure metals se zyada strong, durable aur corrosion resistant hote hain.
• Example: Steel (Iron + Carbon), Brass (Copper + Zinc), Bronze (Copper + Tin).

Conclusion: Metals aur non-metals dono hi apni unique properties ke karan hamari life mein indispensable hain.