Anything that has mass and occupies space is called matter. Everything around us — air, water, food, clothes, even our body — is made up of matter. The ancient Indian philosophers also believed that matter is made of tiny particles, which combine in different ways to form all substances we see around us.
🧩 Characteristics of Particles of Matter
Particles of matter have space between them.
For example, when you mix salt in water, it completely disappears because the salt particles occupy the spaces between water particles.
Particles of matter are constantly moving.
This motion is known as Brownian motion. The speed of motion increases with temperature.
Particles of matter attract each other.
The strength of this attraction varies — it is strongest in solids, weaker in liquids, and weakest in gases.
🧊 States of Matter
Matter mainly exists in three physical states:
Solid – Fixed shape and volume (e.g., ice, wood).
Liquid – Fixed volume but no fixed shape (e.g., water, milk).
Gas – Neither fixed shape nor volume (e.g., air, steam).
Modern science has also identified plasma and Bose–Einstein condensate (BEC) as additional states of matter under extreme conditions.
🔁 Interconversion of States of Matter
Matter can change from one state to another when temperature or pressure is changed.
Change Process Example Solid → Liquid Melting Ice to water Liquid → Gas Vaporisation Water to steam Gas → Liquid Condensation Steam to water Liquid → Solid Freezing Water to ice Solid → Gas Sublimation Camphor or naphthalene balls
These changes are physical and reversible.
🌡️ Latent Heat and Evaporation
When a substance changes its state, its temperature remains constant. The energy absorbed or released during this process is called latent heat —
Latent heat of fusion: heat absorbed to melt a solid.
Latent heat of vaporisation: heat absorbed to convert liquid into gas.
Evaporation
Evaporation is the process by which liquid changes into vapour at room temperature. It causes cooling — for example, sweating helps our body stay cool as the sweat evaporates.
Factors affecting evaporation:
Temperature
Surface area
Humidity
Wind speed
🧠 Real-Life Applications
Desert coolers work better on hot, dry days due to faster evaporation.
Refrigeration uses the principle of evaporation for cooling.
Formation of dew on cold mornings is due to condensation of water vapour.
🌟 Conclusion
“Matter in Our Surroundings” helps us understand that everything in the universe is made of tiny particles, constantly in motion, and always interacting. The concepts of states of matter, latent heat, and evaporation are not just scientific terms — they explain everyday phenomena we experience but rarely stop to think about.
So, the next time you see ice melting or feel the cool breeze from a cooler, remember — you’re watching science in action!
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