Matter Around Us
Introduction
- A simple and important chapter
- Difficult questions may appear in exams, questions may be based on NCERT lines
- Do not take the chapter lightly
What is Matter?
- In chemistry, matter means:
- Which holds mass
- Which occupies space
- Examples: Pen, table, chair, etc.
Physical Properties of Matter
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Matter is made up of small particles
- Small particles are called atoms
- Example with potassium permanganate: Even a small crystal can change the color of water
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There is space between particles
- Example: Salt dissolving in water
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Particles are in continuous motion
- Example: Fragrance of perfume spreading in a room
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Particles attract each other
- Attraction force is strongest in solids and weakest in gases
States of Matter
- Solid: Particles are close together, have a fixed shape
- Liquid: Particles are somewhat apart, no fixed shape
- Gas: Particles are very far apart, no fixed shape
- Additional states: Plasma and Bose-Einstein condensates
Effect of Temperature and Pressure
- Temperature: Increasing temperature increases kinetic energy, decreases attraction force
- Pressure: Opposes the effect of temperature
- Example: Dry ice is stored under high pressure
Evaporation
- The conversion of liquid into vapor, at a temperature below boiling point
- Surface phenomenon
- Evaporation causes cooling
Factors Affecting Evaporation
- Evaporation is affected by: temperature, surface area, humidity, and wind speed
- Example: Water stays cool in a clay pot
Important SI Units
- Temperature is measured in Kelvin
- How to convert Kelvin to Celsius
Cooling Due to Evaporation
- The coolness of water in a clay pot is an example of cooling
- Use of cotton clothes
Questions and Answers
- Important questions from the chapter like the difference between evaporation and boiling, reasons for cooling, etc.
Conclusion
- Have faith in yourself, work hard, and understand questions carefully
Additional Tips
- Every line of NCERT can generate questions
- Learn from solids, liquids, and gases: be strong, adaptable, and flexible
These notes present a summary of the chapter on matter around us and can help in exam preparation.