🔬 The Wonderful World of Science
Class 9 – Chapter 1: Matter in Our Surroundings
Explore what everything around us is made of. Understand particles, states of matter, and how changes in temperature and pressure can transform them.
🌎 What is Matter?
Everything in the universe that has mass and occupies space is called matter. From a tiny grain of sand to a giant star, all are forms of matter. Early philosophers called it the “Panch Tatva” — air, water, fire, earth, and sky.
🔍 Physical Nature of Matter
- 🔸 Matter is made up of tiny particles.
- 🔸 These particles have space between them.
- 🔸 They are constantly moving (kinetic energy).
- 🔸 They attract each other with a certain force.
🔁 States of Matter
Matter exists in three main states: Solid, Liquid, and Gas. They differ in shape, compressibility, flow, and particle arrangement.
- Solids: Fixed shape, volume, and tightly packed particles.
- Liquids: No fixed shape, but fixed volume. Particles are less tightly packed and can slide.
- Gases: Neither fixed shape nor volume. Particles move freely at high speed.
🔥 Change of State
Changing temperature or pressure can convert matter from one state to another:
- ❄️ Melting (Solid → Liquid): Heat overcomes attraction between solid particles.
- 💨 Evaporation (Liquid → Gas): Particles at the surface gain energy and escape.
- 🎈 Condensation, Sublimation & Deposition: Direct changes between gas and solid states.
💧 Evaporation & Cooling
Evaporation is a surface phenomenon. It causes cooling as it absorbs heat from surroundings. Examples:
- 💨 Feeling cool after applying perfume.
- 👕 Cotton clothes absorb sweat and help evaporation.
- 🌬️ Desert coolers work better on dry hot days.
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📊 Quick Quiz
- 1. Which of these is not matter?
🔘 a) Air 🔘 b) Chair 🔘 c) Smell of perfume ✅ 🔘 d) Water - 2. Which state of matter has maximum kinetic energy?
🔘 a) Solid 🔘 b) Liquid 🔘 c) Gas 🔘 d) Plasma - 3. What causes a substance to change its state?
🔘 a) Shape 🔘 b) Mass 🔘 c) Temperature/Pressure 🔘 d) Color
📚 Summary
- ✅ Matter is made of tiny particles that are in constant motion.
- ✅ States of matter can change with temperature or pressure.
- ✅ Evaporation causes cooling.
- ✅ Solid, Liquid, and Gas differ in particle arrangement, movement, and force of attraction.
✍️ Activities
- 💨 Observe evaporation by placing perfume or acetone on your palm.
- 🎈 Explore diffusion by lighting an incense stick in a room.
- 🧪 Try the potassium permanganate dilution experiment.
🌟 Science is Everywhere
From the steam rising from your tea to the clouds above — matter is all around us. Keep exploring!