पदार्थ (Matter) ke Prakar
Matter wo hai jiska mass hota hai aur wo space gherta hai. Matter ko do bhaagon mein baanta gaya hai: Physical Classification (Solid, Liquid, Gas) aur Chemical Classification (Elements, Compounds, Mixtures).
- Element: Wo shuddh padarth jo ek hi type ke atoms se bana ho. Jaise Hydrogen (H), Oxygen (O).
- Compound: Do ya zyada elements chemically combine karke bante hain. Jaise H₂O, CO₂.
- Mixture: Elements ya compounds ka physical combination, jismein alag-alag properties rehti hain. Jaise hawa (air) ek mixture hai.
परमाणु द्रव्यमान और आणविक द्रव्यमान (Atomic Mass and Molecular Mass)
Ek atom ka mass bahut chhota hota hai, isliye hum relative atomic mass ka upyog karte hain. Iska maap 'amu' ya 'u' (atomic mass unit) mein kiya jata hai. 1 amu = 1/12 of mass of C-12 atom.
- Atomic Mass: Ek atom ka average mass relative to C-12. Jaise Carbon ka atomic mass 12 u hai.
- Molecular Mass: Molecule ke andar saare atoms ke atomic masses ka sum. Jaise H₂O ka molecular mass = 2×1 + 16 = 18 u.
Formula Mass
Ionic compounds ke liye 'formula mass' ka concept istemal hota hai. Jaise NaCl ka formula mass = 23 + 35.5 = 58.5 u.
मोल अवधारणा (Mole Concept)
Mole chemistry mein counting ka unit hai. 1 mole mein utne hi particles (atoms, molecules, ions) hote hain jitne 12 g of C-12 mein carbon atoms hote hain (6.022 × 10²³). Is number ko Avogadro number kehte hain.
- Mole Formula: Number of moles (n) = Given mass (m) / Molar mass (M)
- Particles ka hisaab: n = Number of particles / Avogadro constant (Nₐ)
- Gas ke liye: STP par 1 mole gas ka volume 22.4 L hota hai.
रासायनिक संयोजन के नियम (Laws of Chemical Combination)
Yeh wo rules hain jo chemical reactions ko control karte hain:
- Law of Conservation of Mass: Antoine Lavoisier ke anusaar, chemical reaction mein mass na toh create hota hai na destroy. Total mass reactants = Total mass products.
- Law of Definite Proportions (Constant Composition): Joseph Proust ke anusaar, kisi bhi compound mein elements hamesha fixed mass ratio mein hote hain. Jaise H₂O mein hydrogen aur oxygen ka mass ratio hamesha 1:8 hota hai.
- Law of Multiple Proportions: John Dalton ke anusaar, jab do elements different compounds banaate hain, to ek element ke fixed mass ke saath doosre element ke masses simple whole number ratio mein hote hain. Jaise CO aur CO₂ mein, carbon ke fixed mass ke saath oxygen ka mass ratio 1:2 hai.
- Gay Lussac's Law of Gaseous Volumes: Gay Lussac ne bataya ki gases jab react karti hain to unke volumes simple whole number ratio mein hote hain (same temperature and pressure par).
- Avogadro's Law: Same temperature aur pressure par, equal volumes of all gases contain equal number of molecules.
Dalton's Atomic Theory
John Dalton ne 1808 mein yeh theory di. Iske main points hain:
- Har element atoms se bana hota hai jo indivisible hote hain.
- Ek element ke saare atoms same hote hain (mass, size, properties).
- Atoms chemical reactions mein combine hote hain small whole number ratios mein.
- Atoms create ya destroy nahi hote.
महत्वपूर्ण सूत्र (Important Formulas)
- Mole concept: n = m/M, n = V/22.4 (STP), n = N/Nₐ
- Percentage composition: Element ka % = (Mass of element in compound / Molar mass of compound) × 100
- Empirical formula: Sabse simple ratio of atoms. Molecular formula = (Empirical formula)ₙ, jahan n = Molecular mass / Empirical formula mass.
नमूना प्रश्न (Sample Questions)
Q1: 18 g water mein kitne moles hain?
Ans: Molar mass of H₂O = 18 g/mol. n = 18/18 = 1 mole.
Q2: 11 g CO₂ mein kitne carbon atoms hain?
Ans: Moles of CO₂ = 11/44 = 0.25. Carbon atoms = 0.25 × Nₐ = 1.5055 × 10²³ atoms.
Yeh notes aapko Class 11 chemistry ke pehle chapter ki clear understanding denge. Practice karte rahein aur concepts ko repeatedly revise karein.
