Chemistry Study Material (SSC CHSL)

🧪 SSC CHSL Chemistry Study Material – Easy Guide with Emojis

Here’s a simple, emoji-filled summary of the key Chemistry concepts from your SSC CHSL PDF¹:

🌌 Matter & Its States

• Matter is anything that has mass and takes up space (except: heat, light, electricity, sound, magnetism, vacuum, shadow).
• Particles of matter are tiny, have spaces between them, and are always moving (kinetic energy 💨).
• Intermolecular force: Strongest in solids 🧱, weaker in liquids 💧, weakest in gases 💨.

States of Matter

• 🧱 Solid: Fixed shape & volume, particles packed tightly, not compressible.
• 💧 Liquid: No fixed shape, fixed volume, particles move more freely.
• 💨 Gas: No fixed shape or volume, particles move freely, highly compressible.
• 🌟 Plasma: Super-energized, ionized gas (found in stars, neon signs).
• ❄️ Bose-Einstein Condensate: Super-cooled, low-density gas where atoms act as one quantum state.

🔬 Atoms & Molecules

• Atom: Smallest part of an element that can take part in a chemical reaction.
  • Example: Hydrogen atom is the smallest.
• Atomic mass: Measured in atomic mass units (u), based on carbon-12.
• Molecule: Group of two or more atoms bonded together (can be same or different elements).
• Atomicity: Number of atoms in a molecule.
• Ion: Charged particle.
  • Positive = Cation ➕
  • Negative = Anion ➖

⚖️ Laws of Chemistry

• Law of Conservation of Mass: Mass is neither created nor destroyed in a chemical reaction.
• Law of Constant Proportions: Elements in a compound are always in fixed ratios by mass.

🧑‍🔬 Atomic Models

• Dalton’s Atomic Theory:
  • All matter is made of atoms.
  • Atoms can’t be created/destroyed.
  • Atoms of the same element are identical.
• Thomson’s Model: “Plum pudding” – electrons in a positive sphere.
• Rutherford’s Model: Tiny nucleus (positive), electrons revolve around it.
• Bohr’s Model: Electrons in energy levels (shells: K, L, M, N…).

🧩 Subatomic Particles

• Electron (e⁻): Discovered by J.J. Thomson, negative charge.
• Proton (p⁺): Discovered by Goldstein, positive charge.
• Neutron (n⁰): Discovered by Chadwick, neutral.

🧮 Key Atomic Terms

• Atomic Number (Z): Number of protons.
• Mass Number (A): Protons + Neutrons.
• Isotopes: Same atomic number, different mass (e.g., Hydrogen: Protium, Deuterium, Tritium).
• Isobars: Same mass number, different atomic number (e.g., Argon-40 & Calcium-40).
• Isotones: Same number of neutrons.

🧪 Chemical Formulae & Valency

• Chemical formula: Shows which elements and how many atoms are in a compound.
• Valency: Combining capacity of an element (number of electrons lost, gained, or shared).

🧬 Molecular Mass & Avogadro’s Number

• Molecular mass: Sum of atomic masses in a molecule (e.g., H₂O = 2×1 + 16 = 18u).
• Avogadro’s constant: $6.022 \times 10^{23}$ (number of atoms in 12g of carbon-12).

💡 Fun Facts & Exceptions

• Diffusion: Mixing of particles; fastest in gases, slowest in solids.
• Rubber band: Can stretch (solid with flexibility).
• Sponge: Solid but compressible due to air holes.
• Plasma: Found in stars, neon lights.
• BEC: Predicted by S.N. Bose & Einstein, at ultra-low temperatures.

📝 Quick Reference Table

Use these emojis and points to quickly revise Chemistry for SSC CHSL! Good luck! 🍀¹