9th Class Chemistry — Chapter 1: Fundamentals of Chemistry (Notes)

9th Class Chemistry ke Chapter 1 “Fundamentals of Chemistry” ke mukhtasar notes — sirf wo points jo paper me kaam ate hain: definitions, formulas aur wo batain jin par board sawal banata hai. Pehle ye notes parh lein, phir neeche diya gaya quiz de kar apni tayyari khud check kar lein.

Chemistry ki neev — elements, compounds, mixtures aur atomic number — ke ahem points, saral alfaz me.

Bunyadi definitions

• Matter woh cheez hai jis ka wazan ho aur wo jagah gherti ho.
• Element aik hi qisam ke atoms se bani khalis (pure) cheez hai — masalan gold, oxygen, iron.
• Compound do ya zyada elements ke chemical combination se banta hai — masalan water (H₂O), common salt (NaCl).
• Mixture me cheezen sirf milti hain, chemical tor par judti nahi — inhe asani se alag kiya ja sakta hai.
• Homogeneous mixture har jagah aik jaisa hota hai (cheeni mila pani); heterogeneous aik jaisa nahi hota (raait aur pani).
• Atom kisi element ka sab se chhota zarra hai jo chemical reaction me hissa leta hai.
• Ion charge wala atom ya atoms ka group hai — positive ion ko cation aur negative ko anion kehte hain.

Atomic number, mass number aur symbols

• Atomic number (Z) = atom ke nucleus me protons ki tadaad. Har element ki pehchan usi se hoti hai.
• Mass number (A) = protons + neutrons ki tadaad.
• Neutral atom me electrons = protons hote hain.
• Har element ka aik symbol hota hai — pehla harf hamesha capital: Na (sodium), Fe (iron), K (potassium), Ca (calcium).
• Ab tak 118 elements maloom hain, jin me se 92 qudrati tor par milte hain.

Branches of chemistry

• Organic chemistry — carbon ke compounds ka ilm. Inorganic chemistry — baaki elements/compounds ka.
• Physical chemistry — reactions ke usool aur energy. Analytical chemistry — cheezon ki pehchan aur miqdar.
• Biochemistry — zinda organisms ke andar ki chemistry.