Скачать или смотреть Science Ncert Class 9 Chapter 4 परमाणु की संरचना

Chapter 4 me aap atom ke internal structure ko detail me samajhte ho. Pehle scientists sirf itna jaante the ki atom matter ka sabse chhota hissa hai, lekin jaise-jaise research badhi, naye models aur discoveries saamne aati gayi. Is chapter me aap atom ke andar kaise proton, neutron aur electron arranged hote hain, kaise inhe detect kiya gaya, aur inke charges–masses kya hote hain, ye sab padte ho.


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1. Discovery of Electrons, Protons & Neutrons

J.J. Thomson ne electron ki discovery ki aur atom ka pehla model diya.

Goldstein ne proton ki discovery ki.

Chadwick ne neutron ko discover kiya.



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2. Atomic Models

(a) Thomson’s Model

Is model me atom ko “watermelon model” jaisa bataya – jisme positive charge poore atom me phaila hai aur electrons usme embedded hote hain.

(b) Rutherford’s Model

Unhone alpha-particle scattering experiment kiya.

Paya ki atom ka mass aur positive charge nucleus me hota hai.

Electrons nucleus ke around revolve karte hain.

Lekin ye model electron ke girne ka reason nahi bata saka.


(c) Bohr’s Model

Electrons nucleus ke around fixed orbits/shells me ghoomte hain.

In shells me electrons tab tak energy lose nahi karte jab tak fixed orbit me hain.



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3. Atomic Number, Mass Number & Isotopes

Atomic Number (Z) = number of protons.

Mass Number (A) = protons + neutrons.

Isotopes = same atomic number but different mass number.
Example: Hydrogen ke isotopes – Protium, Deuterium, Tritium.

Isobars = same mass number, atomic number alag.



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4. Electron Distribution (Bohr–Bury Rule)

Electrons shells me distribute hote hain (K, L, M, N…).

Formula:

Ek shell me max electrons = 2n²

Example: K = 2, L = 8, M = 18…




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5. Valency

Atom ki combining capacity ko valency kehte hain.
Ye depend karta hai outer shell me kitne electrons hai.


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6. Ions

Electron gain → negative ion (anion)

Electron loss → positive ion (cation)



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Conclusion

Is chapter me aap atom ke internal structure ka complete understanding paate ho—kaise electrons, protons, neutrons arranged hote hain, atom ka model kaise develop hua, aur atomic number/mass number ka kya meaning hota hai. Ye chapter chemistry ki foundation strong banata hai.