Metals ki properties kya hain?

Zyaadatar metals chamakdaar (lustrous) aur sakht hote hain. Ve malleable hain, yaani peetkar patli chaadar ban sakte hain, aur ductile, yaani kheenchkar taar ban sakte hain. Ve sonorous hain, takraane pe khanakte hain, aur garmi aur bijli ke achhe conductors hain. Apvaad bhi hain: sodium aur potassium naram hain, aur mercury drav hai.

Malleability aur ductility mein kya farq hai?

Malleability peetkar patli chaadar banne ka gun hai, jaise aluminium foil ya mithaai pe chaandi ka warq. Ductility kheenchkar taar banne ka gun hai, jaise copper ke bijli ke taar. Gold mein dono bahut hain: ye sabse zyaada malleable metals mein se hai, aur iske ek gram se lagbhag 2 km lamba taar ban sakta hai.

Kya saare metals thos aur sakht hote hain?

Nahi. Sodium aur potassium aise metals hain jo itne naram hain ki chaaku se kat jaate hain, aur mercury, jo pehle thermometer mein hota tha, room temperature pe drav hai. Iron, copper aur aluminium jaise zyaadatar aam metals sakht thos hain.

Metals aur non-metals ki properties

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Lohaar ke paas

Lohaar Sudarshan apni coal ki bhatti mein iron ke tukde ko laal garam karte hain, phir hathode se peetkar use kulhaadi ka aakaar dete hain. Kya doosre padaarth bhi aise aakaar mein dhaale ja sakte hain? Kuch aam padaarthon ki jaanch is sawaal ka jawab deti hai aur dikhati hai ki metals khaas kyun hain.

Chamak aur sakhti

Activity 4.1 mein copper aur aluminium ke tukde, iron ki keel, coal ka tukda, matar jitna sulfur ka dala aur lakdi ka gutka dekhe aur chhooe jaate hain, phir sakht sateh pe hathode se peete jaate hain. Copper, aluminium aur iron chamakdaar (lustrous) hain, metallic lustre waale, aur sakht hain. Ye metals hain. Coal, sulfur aur lakdi dhundhle (non-lustrous) aur utne sakht nahi. Kuch metals pattern todte hain: sodium aur potassium chaaku se kat jaate hain, aur mercury room temperature pe drav hai.

Hathode ke test ke nateeje: copper, aluminium aur iron chamakdaar, sakht aur chapte; coal aur sulfur toot jaate hain; lakdi dono nahi — Hathoda kya dikhata hai

Malleability

Hathode ke neeche copper, aluminium aur iron ki keel chapte ho jaate hain. Peetkar patli chaadar banne ka gun malleability hai, aur zyaadatar metals mein ye hota hai. Kuch mithaiyon pe chaandi ka warq aur khaana lapetne ki aluminium foil aise hi bante hain; gold aur chaandi sabse zyaada malleable metals hain. Coal aur sulfur toot jaate hain, isliye ve bhurbhure (brittle) hain. Lakdi na chaadar banti hai na toot-ti hai, isliye wo na malleable hai na bhurbhuri.

Ductility

Metal ke taar har jagah hain: bijli ki fittings mein copper aur aluminium ke taar, taar ke kangan, haar aur jhumke, veena, sitar, violin ya guitar ke taar, aur chai ki chhanni ki jaali. Kheenchkar taar banne ka gun ductility hai, aur ye mukhya roop se metals mein hota hai; coal ya sulfur ka taar kisi ne nahi dekha. Gold itna ductile hai ki ek gram se lagbhag 2 kilometre lamba taar ban sakta hai. Steel, jo iron aur carbon ka mishran hai, ke taaron ki rassiyan bhaari bojh utha sakti hain, isliye ve jhoolte pulon aur cranes mein lagti hain.

Gold se 2 km ka taar, aur taaron ke upyog: bijli ke taar, sangeet ke taar, gehne aur steel ki rassiyan — Kheenchkar taar: ductility

Sonority

Metal ka chammach aur sikka, phir coal ka tukda aur lakdi ka gutka giraao (Activity 4.2). Chammach aur sikka khanakti aawaaz dete hain; coal aur lakdi dhap ki. Metals ka khanakne ka gun sonority hai, isliye metals sonorous hain. School aur mandir ki ghantiyan aur ghungroo isi se khanakte hain, aur jo vyakti dekh nahi sakta, wo chhadi ki aawaaz se metal aur lakdi mein farq pehchaan sakta hai.

Garmi ka conduction

Activity 4.3 mein lagbhag barabar aakaar ke metal aur lakdi ke chammach garam paani ke gilaas mein kuch minute rakhe jaate hain. Metal ke chammach ka upari sira garam ho jaata hai, jabki lakdi ka chammach thanda rehta hai. Padaarth ke ek bindu se doosre tak garmi ka jaana conduction hai, aur garmi aage badhaane waale padaarth conductors hain. Metals garmi ke achhe conductors hain aur lakdi kharaab, isliye khaana pakaane ke bartan metal ke aur unke handle lakdi ya doosre kharaab conductors ke hote hain.

Garam paani mein metal aur lakdi ke chammach: metal waale ka upari sira garam, lakdi waala thanda — Kaunsa chammach garam hoga?

Bijli ka conduction

Tester circuit, yaani cell, bulb aur gap waale taar, se padaarth jaanche ja sakte hain (Activity 4.4). Aluminium foil, iron ki keel aur copper ka taar bulb jalaate hain; sulfur, coal, sookhi lakdi, patthar, rubber ka eraser aur nylon ki rassi nahi. Bulb jalaane waala har padaarth metal hai. Jo padaarth bijli ko aasaani se behne dein, ve bijli ke achhe conductors hain; jo na dein, ve kharaab conductors. Isiliye electricians plastic ke handle waale screwdriver aur rubber ke dastaane aur joote use karte hain: ye kharaab conductors unhe current ke jhatke se bachaate hain.

Tester circuit iron ki keel se bulb jalaata hai, rubber ke eraser se nahi; achhe aur kharaab conductors ki list — Kya bulb jalega?

Metals aur non-metals ki tulna

Ye kyun zaroori hai

Yahi gun tay karte hain ki kaunsa padaarth kis kaam aaye, taar aur bartan se lekar ghanti aur foil tak. Metals hawa aur paani se kaise reaction karte hain, ye metals mein jang kyun lagta hai aur metal aur non-metal oxides mein hai. Har activity aur sawaal ka jawab Chapter 4 ke NCERT solutions mein hai; poore Chapter 4 ke notes bhi dekho.