Metals and Non-metals

Metals aur non-metals ko unki physical properties ke basis par differentiate karna bahut easy hai. Yeh properties unke daily life uses ko bhi determine karti hain.

Metals ki Physical Properties

• Lustre (चमक): Metals mein metallic lustre hota hai, matlab unki surface shiny hoti hai. Isliye gold aur silver jewellery mein use hote hain.
• Hardness (कठोरता): Generally, metals hard hote hain. Lekin, hardness har metal mein vary karti hai. Example: Sodium (Na) aur Potassium (K) itne soft hote hain ki unhe knife se cut kiya ja sakta hai. Zinc (Zn) aur Lead (Pb) bhi comparatively soft hote hain.
• Malleability (आघातवर्धनीयता): Metals ko patli sheets mein beat kiya ja sakta hai without breaking. Is property ko malleability kehte hain. Gold aur Silver sabse malleable metals hain. Aluminium foils food packaging mein use hoti hain.
• Ductility (तन्यता): Metals ko patle wires mein draw kiya ja sakta hai. Is property ko ductility kehte hain. Gold sabse ductile metal hai (1 gram gold se 2 km long wire ban sakti hai). Copper wires electrical wiring mein use hoti hain.
• Heat Conductivity (ऊष्मा चालकता): Metals good conductors of heat hote hain. Silver (Ag) aur Copper (Cu) best conductors hain. Lead (Pb) aur Mercury (Hg) poor conductors hain. Isliye cooking utensils metals ke bante hain.
• Electrical Conductivity (विद्युत चालकता): Metals good conductors of electricity hote hain. Silver best conductor hai, followed by copper. Isliye electrical wires copper aur aluminium ke bante hain.
• Sonority (ध्वनि): Metals hard surface se strike karne par ringing sound produce karte hain. Is property ko sonority kehte hain. Isliye school bells metals ki banti hain.
• State (अवस्था): Room temperature par sabhi metals solid hote hain, except Mercury (Hg) jo liquid state mein hota hai.
• Melting and Boiling Points: Metals ke high melting aur boiling points hote hain, except Sodium, Potassium, Gallium, aur Caesium.

Non-metals ki Physical Properties

• Lustre: Non-metals mein metallic lustre nahi hota hai. Except Iodine (जो shiny hota hai).
• Hardness: Non-metals generally soft hote hain. Except Diamond (carbon ka allotrope) jo hardest natural substance hai.
• Malleability & Ductility: Non-metals non-malleable aur non-ductile hote hain. Ye brittle hote hain, matlab beat karne par ya stretch karne par break ho jaate hain.
• Heat Conductivity: Non-metals poor conductors of heat hote hain.
• Electrical Conductivity: Non-metals poor conductors of electricity hote hain. Except Graphite (carbon ka allotrope) jo good conductor hai.
• Sonority: Non-metals non-sonorous hote hain.
• State: Non-metals solid, liquid, ya gas teenon states mein exist karte hain. Example: Carbon, Sulphur (solid); Bromine (liquid); Oxygen, Hydrogen (gas).
• Melting and Boiling Points: Non-metals ke low melting aur boiling points hote hain, except Diamond aur Graphite.

Metals ki chemical properties unki reactivity par depend karti hain. Different metals different conditions mein react karte hain.

1. Reaction with Air (Oxygen)

• Almost sabhi metals oxygen ke saath react karke metal oxides banate hain.

\( \text{Metal} + \text{Oxygen} \rightarrow \text{Metal Oxide} \)

• Examples:
• Sodium (Na) aur Potassium (K): Highly reactive. Open air mein vigorously react karte hain aur fire catch kar lete hain. Isliye kerosene oil mein store karte hain.

\( 4\text{Na(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{Na}_2\text{O(s)} \) \( 4\text{K(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{K}_2\text{O(s)} \)

• Magnesium (Mg), Aluminium (Al), Zinc (Zn), Lead (Pb): Air mein slowly react karte hain aur apni surface par oxide layer bana lete hain. Yeh oxide layer further corrosion se protect karti hai.

\( 2\text{Mg(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{MgO(s)} \)

• Iron (Fe): Strong heating par burn nahi karta, lekin iron filings burn vigorously.
• Copper (Cu): Heat karne par burn nahi karta, lekin black copper(II) oxide layer form karta hai.

\( 2\text{Cu(s)} + \text{O}_2\text{(g)} \xrightarrow{\text{Heat}} 2\text{CuO(s)} \)

• Gold (Au), Silver (Ag), Platinum (Pt): High temperatures par bhi oxygen se react nahi karte. Isliye unhe noble metals kehte hain.
• Nature of Metal Oxides:
• Most metal oxides basic in nature hote hain. Water mein dissolve hokar metal hydroxides banate hain.

\( \text{Na}_2\text{O(s)} + \text{H}_2\text{O(l)} \rightarrow 2\text{NaOH(aq)} \)

• Kuch metal oxides, jaise Aluminium oxide (Al}_2\text{O}_3\text{) aur Zinc oxide (ZnO), both acidic aur basic behaviour show karte hain. Inhe amphoteric oxides kehte hain.
• Acid ke saath: \( \text{Al}_2\text{O}_3\text{(s)} + 6\text{HCl(aq)} \rightarrow 2\text{AlCl}_3\text{(aq)} + 3\text{H}_2\text{O(l)} \)
• Base ke saath: \( \text{Al}_2\text{O}_3\text{(s)} + 2\text{NaOH(aq)} \rightarrow 2\text{NaAlO}_2\text{(aq)} + \text{H}_2\text{O(l)} \) (Sodium aluminate)

2. Reaction with Water

• Metals water ke saath react karke metal oxide/hydroxide aur hydrogen gas produce karte hain.

\( \text{Metal} + \text{Water} \rightarrow \text{Metal Oxide/Hydroxide} + \text{Hydrogen gas} \)

• Reactivity Order:
• Potassium (K) aur Sodium (Na): Cold water ke saath vigorously react karte hain. Reaction itni exothermic hoti hai ki hydrogen gas fire catch kar leti hai.

\( 2\text{Na(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{NaOH(aq)} + \text{H}_2\text{(g)} + \text{Heat} \)

• Calcium (Ca): Cold water ke saath less violently react karta hai. Hydrogen gas produce hoti hai, jo calcium surface par stick hokar usko float karati hai.

\( \text{Ca(s)} + 2\text{H}_2\text{O(l)} \rightarrow \text{Ca(OH)}_2\text{(aq)} + \text{H}_2\text{(g)} \)

• Magnesium (Mg): Cold water ke saath react nahi karta. Hot water ke saath react karke magnesium hydroxide aur hydrogen gas banata hai.

\( \text{Mg(s)} + 2\text{H}_2\text{O(hot)} \rightarrow \text{Mg(OH)}_2\text{(aq)} + \text{H}_2\text{(g)} \)

• Aluminium (Al), Iron (Fe), Zinc (Zn): Na cold water se, na hot water se react karte hain. Steam (भाप) ke saath react karke metal oxide aur hydrogen gas banate hain.

\( 2\text{Al(s)} + 3\text{H}_2\text{O(g) (steam)} \rightarrow \text{Al}_2\text{O}_3\text{(s)} + 3\text{H}_2\text{(g)} \) \( 3\text{Fe(s)} + 4\text{H}_2\text{O(g) (steam)} \rightarrow \text{Fe}_3\text{O}_4\text{(s)} + 4\text{H}_2\text{(g)} \)

• Lead (Pb), Copper (Cu), Silver (Ag), Gold (Au): Water (cold, hot, steam) ke saath react nahi karte.

3. Reaction with Acids (Dilute)

• Metals dilute acids ke saath react karke salt aur hydrogen gas produce karte hain.

\( \text{Metal} + \text{Dilute Acid} \rightarrow \text{Salt} + \text{Hydrogen gas} \)

• Reactivity Order:
• Potassium (K), Sodium (Na), Calcium (Ca): Dilute acids ke saath violently react karte hain.
• Magnesium (Mg), Aluminium (Al), Zinc (Zn), Iron (Fe): Dilute HCl ya H}_2\text{SO}_4\text{ ke saath react karke hydrogen gas produce karte hain. Reactivity decrease hoti hai (Mg > Al > Zn > Fe).}

\( \text{Mg(s)} + 2\text{HCl(aq)} \rightarrow \text{MgCl}_2\text{(aq)} + \text{H}_2\text{(g)} \) \( \text{Zn(s)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow \text{ZnSO}_4\text{(aq)} + \text{H}_2\text{(g)} \)

• Copper (Cu), Silver (Ag), Gold (Au), Platinum (Pt): Dilute acids ke saath react nahi karte, kyunki ye hydrogen se less reactive hain.
• Nitric Acid (HNO}_3\text{) ka Special Case: Nitric acid ek strong oxidizing agent hai. Jab metals iske saath react karte hain, toh hydrogen gas produce nahi hoti. Instead, \( \text{H}_2\text{O} \) ban jaata hai aur \( \text{HNO}_3 \) reduce hokar \( \text{NO}_2\text{, NO, N}_2\text{O} \) jaise oxides banata hai. Lekin, Magnesium (Mg) aur Manganese (Mn) very dilute HNO}_3\text{ ke saath react karke hydrogen gas produce karte hain.

4. Reaction with Solutions of other Metal Salts (Displacement Reaction)

• A more reactive metal can displace a less reactive metal from its salt solution.

\( \text{Metal A} + \text{Salt solution of Metal B} \rightarrow \text{Salt solution of Metal A} + \text{Metal B} \)

• Yeh reaction reactivity series par based hoti hai.
• Example: Zinc (Zn) is more reactive than Copper (Cu).

\( \text{Zn(s)} + \text{CuSO}_4\text{(aq)} \rightarrow \text{ZnSO}_4\text{(aq)} + \text{Cu(s)} \) (Zinc displaces Copper from Copper Sulphate solution)

• Example: Copper (Cu) is less reactive than Iron (Fe).

\( \text{Cu(s)} + \text{FeSO}_4\text{(aq)} \rightarrow \text{No reaction} \)

5. Reactivity Series (Activity Series)

• Yeh metals ki list hai jo unki decreasing reactivity ke order mein arranged hai.
• Most Reactive \( \rightarrow \) Least Reactive

K (Potassium) Na (Sodium) Ca (Calcium) Mg (Magnesium) Al (Aluminium) Zn (Zinc) Fe (Iron) Pb (Lead) [H] (Hydrogen - non-metal, reference point) Cu (Copper) Hg (Mercury) Ag (Silver) Au (Gold)

• Key Points:
• Hydrogen se upar wale metals dilute acids se hydrogen displace kar sakte hain.
• Hydrogen se neeche wale metals dilute acids se hydrogen displace nahi kar sakte.
• Jitna upar metal hoga, utna hi reactive hoga aur neeche wale metal ko uske salt solution se displace kar payega.

Chemical Properties of Non-metals

• Reaction with Oxygen: Non-metals oxygen ke saath react karke acidic ya neutral oxides banate hain.
• Acidic oxides: \( \text{C(s)} + \text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)} \) (Carbon dioxide - acidic)
• Neutral oxides: \( \text{C(s)} + \frac{1}{2}\text{O}_2\text{(g)} \rightarrow \text{CO(g)} \) (Carbon monoxide - neutral)
• \( \text{S(s)} + \text{O}_2\text{(g)} \rightarrow \text{SO}_2\text{(g)} \) (Sulphur dioxide - acidic)
• Reaction with Water: Non-metals water ke saath react nahi karte.
• Reaction with Acids: Non-metals dilute acids ke saath react nahi karte.
• Reaction with Salt Solutions: Non-metals generally displacement reactions show nahi karte in the same way as metals.
• Reaction with Hydrogen: Non-metals hydrogen ke saath react karke hydrides banate hain. Example: \( \text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3 \) (Ammonia)

Metals aur non-metals react karke ionic compounds banate hain. Yeh reactions electrons ke transfer par based hoti hain, jisse elements stable electronic configuration (noble gas configuration) achieve karte hain.

1. Electronic Configuration aur Reactivity

• Elements react karte hain taaki unke outermost shell mein 8 electrons (octet) ya 2 electrons (duplet, for H, He, Li) complete ho jaaye.
• Metals: Metals ke outermost shell mein 1, 2, ya 3 electrons hote hain. Yeh electrons lose karke positive ions (cations) banate hain aur noble gas configuration achieve karte hain.
• Example: Sodium (Na) Atomic No. 11 (2, 8, 1) \( \rightarrow \) \( \text{Na}^+ \) (2, 8) + \( \text{e}^- \)
• Example: Magnesium (Mg) Atomic No. 12 (2, 8, 2) \( \rightarrow \) \( \text{Mg}^{2+} \) (2, 8) + \( 2\text{e}^- \)
• Non-metals: Non-metals ke outermost shell mein 5, 6, ya 7 electrons hote hain. Yeh electrons gain karke negative ions (anions) banate hain aur noble gas configuration achieve karte hain.
• Example: Chlorine (Cl) Atomic No. 17 (2, 8, 7) + \( \text{e}^- \) \( \rightarrow \) \( \text{Cl}^- \) (2, 8, 8)
• Example: Oxygen (O) Atomic No. 8 (2, 6) + \( 2\text{e}^- \) \( \rightarrow \) \( \text{O}^{2-} \) (2, 8)

2. Ionic Compounds (Electrovalent Compounds)

• Compounds jo electrons ke transfer se metal aur non-metal ke beech bante hain, unhe ionic compounds kehte hain.
• Formation of Sodium Chloride (NaCl):
• Sodium (Na) ek electron lose karta hai aur \( \text{Na}^+ \) ion banata hai.
• Chlorine (Cl) woh electron gain karta hai aur \( \text{Cl}^- \) ion banata hai.
• Oppositely charged ions (\( \text{Na}^+ \) aur \( \text{Cl}^- \)) ke beech strong electrostatic force of attraction develop hota hai, jisse NaCl banta hai.

\( \text{Na} \rightarrow \text{Na}^+ + \text{e}^- \) \( \text{Cl} + \text{e}^- \rightarrow \text{Cl}^- \) \( \text{Na}^+ + \text{Cl}^- \rightarrow \text{NaCl} \)

• Formation of Magnesium Chloride (MgCl}_2\text{):
• Magnesium (Mg) do electrons lose karta hai aur \( \text{Mg}^{2+} \) ion banata hai.
• Do Chlorine atoms har ek electron gain karte hain aur do \( \text{Cl}^- \) ions banate hain.

\( \text{Mg} \rightarrow \text{Mg}^{2+} + 2\text{e}^- \) \( 2\text{Cl} + 2\text{e}^- \rightarrow 2\text{Cl}^- \) \( \text{Mg}^{2+} + 2\text{Cl}^- \rightarrow \text{MgCl}_2 \)

3. Properties of Ionic Compounds

• Physical Nature: Ionic compounds solid aur hard hote hain, kyunki positive aur negative ions ke beech strong electrostatic forces of attraction hote hain. Yeh brittle bhi hote hain.
• Melting and Boiling Points: Inke high melting aur boiling points hote hain, kyunki strong inter-ionic forces ko overcome karne ke liye considerable energy ki requirement hoti hai.
• Solubility: Ionic compounds generally water mein soluble hote hain, lekin organic solvents (jaise kerosene, petrol) mein insoluble hote hain.
• Electrical Conductivity:
• Solid state mein: Ionic compounds electricity conduct nahi karte, kyunki ions rigid structure mein fixed hote hain aur move nahi kar sakte.
• Molten state ya aqueous solution mein: Ionic compounds electricity conduct karte hain, kyunki molten state mein ya water mein dissolve karne par ions free ho jaate hain aur current carry kar sakte hain.

Earth's crust metals ka main source hai. Metals ko unke ores se extract karne aur refine karne ke process ko Metallurgy kehte hain.

1. Key Terms

• Minerals: Elements ya compounds jo naturally earth's crust mein occur karte hain.
• Ores: Woh minerals jinse metal ko profitably extract kiya ja sakta hai. Har ore mineral hota hai, par har mineral ore nahi hota.
• Gangue: Ores mein present undesirable impurities jaise soil, sand, rocky material.

2. Steps in Metallurgy

Metals ke extraction mein mainly teen steps hote hain:

1. Enrichment of Ores (Concentration of Ores)
2. Extraction of Metal from Concentrated Ore
3. Refining of Metal

3. Enrichment of Ores

• Is step mein gangue ko ore se remove kiya jaata hai.
• Methods gangue aur ore ki physical aur chemical properties par depend karte hain (e.g., hydraulic washing, magnetic separation, froth flotation).

4. Extraction of Metals (Reactivity Series ke basis par)

Metals ki reactivity ke according unhe extract karne ke different methods hain:

A. Extracting Metals Low in the Activity Series (e.g., Hg, Cu, Ag)

• Yeh metals least reactive hote hain aur often free state mein milte hain (Ag, Au, Pt).
• Inke oxides ko sirf heat karke metal mein reduce kiya ja sakta hai.
• Cinnabar (HgS): Mercury ka ore. Heat karne par mercury(II) oxide banta hai, further heat karne par mercury metal.

\( 2\text{HgS(s)} + 3\text{O}_2\text{(g)} \xrightarrow{\text{Heat}} 2\text{HgO(s)} + 2\text{SO}_2\text{(g)} \) \( 2\text{HgO(s)} \xrightarrow{\text{Heat}} 2\text{Hg(l)} + \text{O}_2\text{(g)} \)

• Copper (Cu): Cuprum sulphide (\( \text{Cu}_2\text{S} \)) ko air mein heat karne par copper metal milta hai.

\( 2\text{Cu}_2\text{S(s)} + 3\text{O}_2\text{(g)} \xrightarrow{\text{Heat}} 2\text{Cu}_2\text{O(s)} + 2\text{SO}_2\text{(g)} \) \( 2\text{Cu}_2\text{O(s)} + \text{Cu}_2\text{S(s)} \xrightarrow{\text{Heat}} 6\text{Cu(s)} + \text{SO}_2\text{(g)} \)

B. Extracting Metals in the Middle of the Activity Series (e.g., Zn, Fe, Pb, Cu)

• Yeh metals moderately reactive hote hain aur usually sulphide ya carbonate ores ke form mein milte hain.
• Inhe pehle oxides mein convert karte hain, kyunki oxides ko reduce karna easier hota hai.
• Sulphide ores: Roasting process se oxides mein convert karte hain. Roasting mein ore ko excess air mein strongly heat karte hain.

\( 2\text{ZnS(s)} + 3\text{O}_2\text{(g)} \xrightarrow{\text{Roasting}} 2\text{ZnO(s)} + 2\text{SO}_2\text{(g)} \)

• Carbonate ores: Calcination process se oxides mein convert karte hain. Calcination mein ore ko limited air mein strongly heat karte hain.

\( \text{ZnCO}_3\text{(s)} \xrightarrow{\text{Calcination}} \text{ZnO(s)} + \text{CO}_2\text{(g)} \)

• Reduction of Metal Oxides: Metal oxides ko carbon (coke) jaise reducing agents se reduce kiya jaata hai.

\( \text{ZnO(s)} + \text{C(s)} \xrightarrow{\text{Heat}} \text{Zn(s)} + \text{CO(g)} \)

• Displacement Reactions: Kuch metals ko unke oxides se displace karke bhi extract kiya jaata hai. Example: Manganese dioxide ko Aluminium powder se reduce karna.

\( 3\text{MnO}_2\text{(s)} + 4\text{Al(s)} \rightarrow 3\text{Mn(l)} + 2\text{Al}_2\text{O}_3\text{(s)} + \text{Heat} \)

• Thermit Reaction: Iron oxide (Fe2O3) ko Aluminium se reduce karne par molten iron produce hota hai. Yeh reaction highly exothermic hoti hai aur railway tracks aur cracked machine parts ko join karne mein use hoti hai.

\( \text{Fe}_2\text{O}_3\text{(s)} + 2\text{Al(s)} \rightarrow 2\text{Fe(l)} + \text{Al}_2\text{O}_3\text{(s)} + \text{Heat} \)

C. Extracting Metals towards the Top of the Activity Series (e.g., K, Na, Ca, Mg, Al)

• Yeh metals highly reactive hote hain aur carbon se reduce nahi ho sakte, kyunki unki carbon se affinity oxygen ke liye zyada hoti hai.
• Inhe electrolytic reduction se extract kiya jaata hai (molten state mein).
• Molten NaCl ka Electrolysis: Sodium metal cathode par deposit hota hai aur chlorine gas anode par evolve hoti hai.
• At Cathode: \( \text{Na}^+ + \text{e}^- \rightarrow \text{Na} \)
• At Anode: \( 2\text{Cl}^- \rightarrow \text{Cl}_2 + 2\text{e}^- \)
• Similarly, Aluminium ko molten \( \text{Al}_2\text{O}_3 \) ke electrolysis se obtain kiya jaata hai.

5. Refining of Metals

• Extraction ke baad metals mein impurities hoti hain. In impurities ko remove karke pure metal obtain karne ko refining kehte hain.
• Electrolytic Refining: Most widely used method. Copper, Zinc, Tin, Nickel, Silver, Gold jaise metals ko refine karne ke liye use hota hai.
• Anode: Impure metal (thick block)
• Cathode: Pure metal ki thin strip
• Electrolyte: Metal salt solution (e.g., Copper refining ke liye acidified \( \text{CuSO}_4 \) solution)
• Process: Current pass karne par, anode se impure metal dissolve hokar electrolyte mein jaata hai. Electrolyte se pure metal ions cathode par deposit ho jaate hain. Insoluble impurities anode mud ke form mein anode ke neeche settle ho jaati hain.
• At Anode: \( \text{M} \rightarrow \text{M}^{n+} + n\text{e}^- \) (Impure metal dissolve hota hai)
• At Cathode: \( \text{M}^{n+} + n\text{e}^- \rightarrow \text{M} \) (Pure metal deposit hota hai)

Corrosion ek natural process hai jismein refined metal slowly deteriorate hota hai environment ke saath chemical ya electrochemical reaction se.

1. Rusting of Iron

• Iron objects ko moist air mein long time tak expose karne par brown flaky substance (rust) ki coating aa jaati hai. Is process ko rusting kehte hain.
• Rust ka chemical formula: Hydrated Iron(III) oxide (Fe}_2\text{O}_3 \cdot \text{xH}_2\text{O}).
• Conditions for Rusting: Rusting ke liye both oxygen (air) aur water (moisture) necessary hain.
• Activity: 3 test tubes (A, B, C)
• A: Iron nail + water + air \( \rightarrow \) Rusting
• B: Iron nail + boiled distilled water (no dissolved air) + oil layer (prevents air entry) \( \rightarrow \) No rusting
• C: Iron nail + anhydrous calcium chloride (absorbs moisture) + dry air \( \rightarrow \) No rusting
• Conclusion: Rusting ke liye air aur water dono chahiye.

2. Corrosion of other Metals

• Copper: Moist air mein copper greenish layer (basic copper carbonate, CuCO}_3 \cdot \text{Cu(OH)}_2\text{) develop karta hai. Isliye tarnished copper vessels ko lemon ya tamarind juice se clean karte hain, kyunki acid is basic layer ko dissolve kar deta hai.
• Silver: Air mein silver articles black ho jaate hain due to reaction with \( \text{H}_2\text{S} \) gas to form silver sulphide (\( \text{Ag}_2\text{S} \)).

3. Prevention of Corrosion

Corrosion se metals ko protect karne ke several methods hain:

• Painting: Iron articles par paint karne se air aur moisture ka contact cut ho jaata hai.
• Oiling/Greasing: Moving parts par oil ya grease lagane se friction reduce hota hai aur corrosion bhi prevent hota hai.
• Galvanisation: Steel aur iron ko thin layer of zinc se coat karna. Zinc iron se zyada reactive hota hai, isliye zinc corrode hota hai aur iron protected rehta hai (sacrificial protection).
• Chrome Plating: Chromium ki layer deposit karna (e.g., car parts, bicycle handlebars).
• Anodising: Aluminium par thick oxide layer banana. Aluminium air ke saath react karke natural oxide layer banata hai, anodising se is layer ko thick banaya jaata hai, jo further corrosion resistant hoti hai.
• Making Alloys: Metals ko alloys mein convert karna corrosion resistance improve karta hai.

4. Alloys

• Alloy ek homogeneous mixture hota hai do ya do se zyada metals ka, ya ek metal aur ek non-metal ka.
• Alloys ki properties unke constituent metals se different hoti hain, often improved hoti hain (e.g., increased hardness, corrosion resistance).
• Examples:
• Steel: Iron + Carbon (harder, stronger than pure iron)
• Stainless Steel: Iron + Nickel + Chromium (corrosion resistant)
• Brass: Copper + Zinc
• Bronze: Copper + Tin
• Solder: Lead + Tin (low melting point, electrical wiring mein use hota hai)
• Amalgam: Mercury ke saath kisi bhi metal ka alloy. Dental fillings mein use hota hai.
• Why Alloying? Alloying se metal ki properties ko desired way mein change kiya ja sakta hai (e.g., iron ko rust-proof banana, gold ko hard banana).
• Pure gold (24 carat) bahut soft hota hai, isliye jewellery banane ke liye isme copper ya silver mix karte hain (22 carat gold).