1. Matter:

  • Everything around us is made of matter—air, food, stones, animals, plants, even tiny things like a grain of sand or a drop of water.
  • Matter has two key properties:
    • Mass: The amount of matter in something (measured in kilograms, kg).
    • Volume: The amount of space something occupies (measured in cubic meters, m³, or liters, L).

2. Historical Classifications of Matter:

  • Ancient Indian philosophers classified matter as five basic elements—Panch Tatva (air, earth, fire, sky, water).
  • Greek philosophers had a similar view.
  • Modern science uses two classifications based on physical properties (like shape and texture) and chemical properties (how substances react). This chapter focuses on the physical nature.

3. Physical Nature of Matter:

  • Matter is made up of particles: Two views about the nature of matter—either it’s a continuous block or made up of tiny particles. Modern science supports the idea that matter is particulate (like sand).
  • Experiments:
    • Salt dissolving in water: When salt dissolves, it spreads throughout the water. This shows matter is made of particles that can mix and occupy the space between other particles.
    • Potassium permanganate in water: Even when diluted many times, the color is still visible, indicating the presence of tiny particles.

4. How Small are Particles of Matter?:

  • Particle size: Even a small amount of substance, like a few crystals of potassium permanganate, can color a large amount of water. This shows that matter is made of very tiny particles.
  • Dilution: As we dilute substances, the particles keep getting smaller and smaller but are still present, showing that the particles are very tiny and can spread over large areas.

5. Characteristics of Particles of Matter:

  • Particles are constantly moving: This movement is called kinetic energy. Higher temperature means faster movement.
  • Diffusion: The process by which particles of different substances mix with each other, like when perfume spreads in the air. Diffusion happens faster at higher temperatures.
  • Attraction between particles: Particles in matter attract each other. The strength of this attraction varies (like in solids, liquids, and gases).

6. Types of Matter:

Matter exists in three states: solid, liquid, and gas. Each has its own properties because of the different behaviors of particles in each state.

6.1 Solid State:

  • Characteristics: Solids have a definite shape and volume. The particles are closely packed and cannot move freely, which is why solids maintain their shape.
  • Example: A rubber band changes shape when stretched, but it remains solid.
  • Compressibility: Solids have very little compressibility, meaning they can’t be easily compressed.

6.2 Liquid State:

  • Characteristics: Liquids have a fixed volume but no fixed shape. They take the shape of the container they are in. The particles in liquids have more space to move compared to solids.
  • Example: Water flows and changes shape when poured from one container to another.
  • Diffusion: Liquids can mix with solids and gases, and diffusion happens faster in liquids than in solids because the particles in liquids are more spread out.

6.3 Gas State:

  • Gases have neither fixed shape nor fixed volume. They expand to fill any space. Particles in gases are far apart and move freely, making them highly compressible.

Key Concepts for Competitive Exams:

  • Matter is everywhere and comes in different forms—solid, liquid, and gas.
  • Mass and Volume are fundamental properties used to measure and differentiate between different substances.
  • Kinetic Energy: All particles of matter are always in motion; heating them increases their movement.
  • Diffusion: The process by which particles spread out from areas of higher concentration to lower concentration. This happens faster in liquids and gases.
  • States of Matter: The properties of matter depend on the state (solid, liquid, gas), and the temperature can change the state.

Gaseous State and Properties of Gases:

  • Compressibility: Gases can be compressed much more than solids and liquids. For example, gases like LPG (Liquefied Petroleum Gas) and CNG (Compressed Natural Gas) are stored in cylinders in compressed form to save space and make transportation easier.
  • Diffusion: Gases spread out to fill any space. For instance, the smell of food spreads from the kitchen to other rooms because gas molecules move quickly and mix with air molecules. This property of gases is called diffusion and is much faster than in solids or liquids due to the higher speed of their particles.

2. Random Motion of Gas Particles:

  • Gas particles are always moving randomly at high speed. They collide with each other and with the walls of the container. The force of these collisions causes pressure. Pressure is defined as the force exerted by gas particles per unit area on the walls of the container.

3. Change of Temperature and Its Effect on Matter:

  • Heating Solids: When a solid is heated, its particles gain kinetic energy and start moving faster. This leads to the solid melting into a liquid (fusion).
  • Melting Point: The temperature at which a solid melts is called its melting point. For example, ice melts at 273.15 K (0°C).
  • Latent Heat: When a substance melts, the temperature doesn’t increase until the entire solid has turned into liquid. The heat energy used during this phase change is called latent heat. This energy is hidden in the substance and doesn’t show up as an increase in temperature.

4. Boiling and Evaporation:

  • Boiling Point: The temperature at which a liquid turns into a gas is called its boiling point. Water, for instance, boils at 373 K (100°C) at standard atmospheric pressure.
  • Latent Heat of Vaporization: The heat required to turn 1 kg of liquid into gas at its boiling point is called latent heat of vaporization.

5. Change of State:

  • Substances can change between solid, liquid, and gas states by changing temperature. Some substances also change directly from solid to gas or vice versa.
    • Sublimation: The process where a solid turns directly into a gas without becoming liquid (e.g., camphor or dry ice).
    • Deposition: The reverse process, where a gas turns directly into a solid (e.g., frost formation).

6. Effect of Pressure on States of Matter:

  • Pressure and Particle Movement: The pressure applied to a substance affects how close its particles can get. High pressure can squeeze gas particles together, making them behave more like a liquid or solid.
  • Gaseous to Solid Transformation: Dry ice (solid CO2) sublimates at 1 atmosphere pressure (changing directly from solid to gas), without going through the liquid phase. This happens due to the nature of CO2’s sublimation point.

7. Temperature and Pressure Combined:

  • The state of a substance (solid, liquid, gas) depends on both temperature and pressure.
  • High pressure and low temperature can liquefy gases, while low pressure and high temperature can cause solids to sublimate directly to gases.

8. Key Terms:

  • Density: Mass per unit volume. Gases, generally, have lower density compared to liquids and solids.
  • Kinetic Energy: The energy of motion. In gases, particles have high kinetic energy, which is why gases spread so quickly (diffusion) and exert pressure.

9. Examples of Matter Changing States:

  • Ice to Water (Fusion): Melting of ice occurs when heat is applied, and the temperature remains constant during the phase change.
  • Water to Steam (Vaporization): Water boils when heated to its boiling point, and energy is required to convert it into steam without raising the temperature further.

Additional Knowledge for Competitive Exams:

  • Boyle’s Law: At constant temperature, the volume of a gas is inversely proportional to its pressure (P ∝ 1/V).
  • Charles’s Law: At constant pressure, the volume of a gas is directly proportional to its temperature (V ∝ T).
  • Ideal Gas Law: Relates pressure, volume, and temperature of gases: PV = nRT (where P = pressure, V = volume, n = number of moles, R = gas constant, and T = temperature).
  • Dalton’s Law of Partial Pressures: The total pressure exerted by a mixture of non-reacting gases is the sum of the partial pressures of the individual gases.

THESE ALL ARE THE NOTES OF CHAPTER 1 SCIENCE. AND AFTER SOME TIME YOU GET IMPORTANT QUESTIONS HERE. *#THANKS FOR VISITING, VISIT AGAIN#* 😊