Chapter 1: Matter in Our Surrounding

Source: rdphyzics.blogspot.com

Definition of Matter:

• Everything in the universe is made of material called matter.
• Examples: Air, food, stones, clouds, stars, plants, animals, water, sand, etc.

Characteristics of Matter

• Occupies space (volume).
• Has mass.

Historical Understanding of Matter

Early Indian Philosophers: Classified matter into five basic elements (Panch Tatva):

1. Air
2. Earth
3. Fire
4. Sky
5. Water

Belief: Everything (living and non-living) is composed of these elements.

Ancient Greek Philosophers: Developed a similar classification.

Modern Classification of Matter

Based on:

1. Physical properties.
2. Chemical nature.

Focus of the Chapter: Study of matter based on physical properties.

Key Terms

• Mass: The amount of matter in an object.
• Volume: The space occupied by matter.

Matter is Made Up of Particles

• Two Theories about Matter's Nature:
  1. Matter is continuous (e.g., like a block of wood).
  2. Matter is particulate (e.g., like sand).
• Activity 1.1: Dissolving Salt/Sugar in Water
  1. Fill a beaker halfway with water and mark the water level.
  2. Add salt or sugar and stir with a glass rod.
  3. Observe changes in water level.
• Observations:
  1. Salt/sugar dissolves and spreads throughout the water.
  2. Water level does not change.
• Conclusion:
  1. Particles of salt/sugar fit into the spaces between particles of water, showing that matter is made of particles.

How Small Are the Particles of Matter?

• Activity 1.2: Dissolving Potassium Permanganate
  1. Dissolve 2-3 crystals of potassium permanganate in 100 mL of water.
  2. Take 10 mL of this solution and dilute it in another 100 mL of water.
  3. Repeat the process several times.
• Observations:
  1. The solution becomes lighter in color with each dilution but remains visible.
  2. A single crystal of potassium permanganate can color a large volume of water (~1000 L).
• Conclusion:
  1. Particles of matter are extremely small, dividing further and further with each dilution.
• Alternate Example Using Dettol:
  1. Replace potassium permanganate with 2 mL of Dettol.
  2. The smell of Dettol is detectable even after repeated dilution, proving that particles of matter are very small.

Key Points

• Matter is particulate in nature.
• Particles of matter are extremely small, beyond ordinary imagination.
• The SI unit of mass is kilogram (kg).
• The SI unit of volume is cubic meter (m³).
  • Common units: 1 liter (L) = 1 dm³ = 1000 mL = 1000 cm³.

Characteristics of Particles of Matter

1) Particles of Matter Have Space Between Them

• Observations from Activities (1.1 and 1.2):
  • Sugar, salt, Dettol, or potassium permanganate particles spread evenly in water.
  • When making tea, coffee, or lemonade, particles of one type of matter fill the spaces between particles of another type.
  • Conclusion: Particles of matter have spaces between them.

2) Particles of Matter Are Continuously Moving

• Activity 1.3 (Incense Stick):
  • Unlit incense stick: Smell is detected only when close.
  • Lit incense stick: Smell spreads across the room.
  • Observation: Particles of matter move and spread in all directions.
• Activity 1.4 (Ink and Honey in Water):
  • Ink spreads evenly throughout water over time.
  • Honey takes longer to mix.
  • Observation: Particles of liquids move and mix on their own.
• Activity 1.5 (Potassium Permanganate in Hot and Cold Water):
  • Crystals dissolve faster in hot water than in cold water.
  • Conclusion: Particles of matter possess kinetic energy and move continuously.
  • Higher temperature increases kinetic energy, leading to faster movement and diffusion.

3) Particles of Matter Attract Each Other

• Activity 1.6 (Human Chain Game):
  • Groups with locked arms are harder to break than those holding hands or touching fingertips.
  • Conclusion: The force of attraction between particles varies in strength.
• Activity 1.7 (Breaking Substances):
  • Iron nail: Hardest to break.
  • Chalk: Easier to break.
  • Rubber band: Stretchable but cohesive.
  • Conclusion: Iron particles have the strongest attraction, followed by chalk, then rubber.
• Activity 1.8 (Cutting Water Surface):
  • Water surface remains intact despite attempts to cut it.
  • Conclusion: Particles of matter are held together by forces of attraction.

Key Points

1. Space Between Particles: Particles of matter have spaces between them.
2. Continuous Motion: Particles are in constant motion due to kinetic energy. Motion increases with temperature.
3. Force of Attraction: Particles of matter attract each other. The strength of attraction varies for different types of matter.

States of Matter

Matter exists in three primary states:

• Solid: Has a definite shape and volume.
• Liquid: Has a definite volume but takes the shape of its container.
• Gas: Has no fixed shape or volume and expands to fill its container.

1) The Solid State

Characteristics of Solids:

• Definite shape and distinct boundaries.
• Fixed volume with negligible compressibility.
• Rigid; solids maintain their shape under outside force, though they may break.

Examples and Exceptions:

• Rubber band: Changes shape under force but regains it when the force is removed.
• Sugar and salt: Individual crystals have fixed shapes regardless of the container.
• Sponge: Compressible due to air trapped in its holes, but it is still a solid.

2) The Liquid State

Characteristics of Liquids:

• No fixed shape but a fixed volume.
• Take the shape of the container.
• Flow and change shape, making them fluids.

Diffusion in Liquids:

• Solids, liquids, and gases can diffuse into liquids.
• The rate of diffusion is higher in liquids than solids due to greater particle movement and more space between particles.

Essential for Life:

• Dissolved gases (oxygen, carbon dioxide) in water are crucial for the survival of aquatic life.

3) The Gaseous State

Characteristics of Gases:

• Highly compressible.
• Take the shape and volume of their container.

Applications of Compressibility:

• LPG cylinders for cooking.
• Compressed Natural Gas (CNG) as a vehicle fuel.
• Oxygen cylinders for medical use.

Diffusion in Gases:

• Gases diffuse quickly due to high particle speed and large spaces between particles.
• Example: The smell of food reaching from the kitchen quickly.

Random Particle Movement:

• Gas particles move randomly at high speed.
• Gas pressure results from particles colliding with the container walls.

Activity Observations:

• Gases are easily compressible, while liquids and solids resist compression.

Comparison of States of Matter

Property	Solid	Liquid	Gas
Shape	Fixed	Not fixed	Not fixed
Volume	Fixed	Fixed	Not fixed
Compressibility	Negligible	Low	High
Particle Movement	Vibrations in fixed positions	Freely move within limits	Random and fast motion
Diffusion Rate	Very slow	Faster than solids	Fastest

• Solid: Particles tightly packed with no motion.
• Liquid: Particles loosely packed, moving freely.
• Gas: Particles far apart, moving randomly.

States of Water

• Water exists in three states:
  • Solid: Ice
  • Liquid: Water
  • Gas: Water vapor

Effect of Temperature on States of Matter

a) Heating Solids

• Increases kinetic energy of particles.
• Particles vibrate faster and overcome forces of attraction.
• Solid melts into liquid at the melting point.
• Melting Point: The temperature at which a solid turns into a liquid at atmospheric pressure.
  • Example: Ice melts at 273.15 K (0°C).
• Latent Heat of Fusion: Heat energy required to convert 1 kg of solid into liquid at its melting point without changing temperature.

b) Heating Liquids

• Particles move faster with more heat.
• At the boiling point, particles have enough energy to break free and become gas.
• Boiling Point: The temperature at which a liquid turns into gas at atmospheric pressure.
  • Example: Water boils at 373 K (100°C).
• Latent Heat of Vaporization: Heat energy required to convert 1 kg of liquid into gas at its boiling point without changing temperature.

c) Energy Comparison

• Particles in water at 0°C (273 K) have more energy than particles in ice at the same temperature due to latent heat of fusion.
• Particles in steam at 100°C (373 K) have more energy than particles in water at the same temperature due to latent heat of vaporization.

Sublimation and Deposition

a) Sublimation

• Direct change from solid to gas without passing through the liquid state.
• Example: Camphor, ammonium chloride.

b) Deposition

• Direct change from gas to solid without passing through the liquid state.

4. SI Unit of Temperature

• Kelvin (K) is the SI unit of temperature.
  • Conversion:
    • Celsius to Kelvin: Add 273.
    • Kelvin to Celsius: Subtract 273.

5. Key Definitions

• Fusion: Change of state from solid to liquid.
• Latent Heat of Fusion: Heat needed to melt a solid at its melting point.
• Boiling Point: Temperature where liquid changes to gas.
• Latent Heat of Vaporization: Heat needed to vaporize a liquid at its boiling point.
• Sublimation: Solid changes directly to gas.
• Deposition: Gas changes directly to solid.

Key Observations from Activities

• Activity 1.12: Temperature remains constant during melting and boiling until the change of state is complete.
• Activity 1.13: Sublimation observed with camphor/ammonium chloride. Direct transformation between solid and gas states bypasses the liquid state.

Practice MCQ Questions 👈👈

Effect of Change of Pressure on Matter

• Pressure and State of Matter:
  • The state of matter (solid, liquid, or gas) is influenced by the distances between the particles.
  • When pressure is applied to a gas, the particles come closer to each other, and the gas may be compressed.
  • By applying pressure and reducing the temperature, gases can be liquefied.
• Example of Solid CO₂ (Dry Ice):
  • Solid carbon dioxide (CO₂) is stored under high pressure.
  • When the pressure is reduced to 1 atmosphere, solid CO₂ converts directly into gas without going through the liquid state. This phenomenon is called sublimation.
  • Solid CO₂ is also known as dry ice due to its ability to sublimate directly to gas.
• Pressure and Temperature Influence:
  • Both pressure and temperature play a significant role in determining the state of a substance.
  • High pressure and low temperature can transform gases into liquids or solids.
  • The balance of these factors dictates whether a substance will be in a solid, liquid, or gas state.
• Units of Pressure:
  • The unit of pressure is Pascal (Pa), with 1 atmosphere (atm) being equal to 1.01 × 10⁵ Pa.
  • The normal atmospheric pressure at sea level is 1 atmosphere (atm), and it is used as a reference for measuring gas pressures.

Practice MCQ Questions 👈👈

Evaporation:

• Evaporation is the process where a liquid changes into vapor at a temperature below its boiling point.
• This happens when the particles at the surface of the liquid gain enough kinetic energy to break free from the forces of attraction between particles and transition into the vapor state.

Examples of Evaporation:

• Water left uncovered slowly changes into vapor.
• Wet clothes dry up due to evaporation.

Factors Affecting Evaporation:

1. Temperature:
   • The rate of evaporation increases with the increase in temperature. Higher temperatures provide more kinetic energy to the particles, allowing more of them to escape into the vapor state.
2. Surface Area:
   • The rate of evaporation increases when the surface area of the liquid is larger. Evaporation is a surface phenomenon, so increasing the exposed surface allows more particles to escape into the air. For example, spreading out clothes increases the rate at which they dry.
3. Humidity:
   • Humidity is the amount of water vapor present in the air. If the surrounding air already contains a high amount of water vapor, the rate of evaporation decreases. The air has less capacity to hold more water vapor at a given temperature.
4. Wind Speed:
   • The rate of evaporation increases with the increase in wind speed. Wind moves the water vapor away from the surface, reducing the local humidity and allowing more liquid to evaporate. This is why clothes dry faster on windy days.

Key Concepts:

• Evaporation happens below the boiling point.
• Evaporation depends on surface area, temperature, humidity, and wind speed.
• The more the surface area and temperature, the faster the evaporation.
• Higher humidity slows down evaporation, while wind speed accelerates it.

Practice MCQ Questions 👈👈

Fifth States of Matter:

1. Plasma:

   • Plasma is a state of matter consisting of super energetic and highly excited particles, often in the form of ionized gases.
   • Properties:
     • The particles in plasma are charged (ions and electrons).
     • Plasma does not have a fixed shape or volume like solids and liquids but behaves more like a gas.
     • It glows with specific colors depending on the type of gas and energy supplied.
   • Examples:
     • Neon signs and fluorescent tubes contain plasma, where gases (such as neon or helium) get ionized when an electrical current flows through them, creating glowing plasma.
     • The Sun and other stars are made up of plasma due to their extremely high temperatures.

2. Bose-Einstein Condensate (BEC):

   • The BEC is the fifth state of matter, first proposed by Satyendra Nath Bose and later predicted by Albert Einstein.
   • Formation:
     • A BEC is formed by cooling a gas of extremely low density to near absolute zero (super low temperatures).
     • The gas particles slow down and group together, acting as a single quantum entity.
     • The density of the gas is about one-hundred-thousandth the density of normal air.
   • Achievement:
     • The Nobel Prize in Physics 2001 was awarded to Eric A. Cornell, Wolfgang Ketterle, and Carl E. Wieman for achieving Bose-Einstein condensation in a lab.
   • Properties:
     • At temperatures close to absolute zero, the atoms in the gas collapse into a single quantum state, behaving like a single super atom.
     • BEC is an exotic state of matter with unusual quantum properties, making it a subject of much research.

Watch video: Bose Einstein Condensate

Units of Measurement

Quantity	Unit	Symbol
Temperature	Kelvin	K
Length	Metre	m
Mass	Kilogram	kg
Weight	Newton	N
Volume	Cubic Metre	m3
Density	Kilogram per Cubic Metre	kg m-3
Pressure	Pascal	Pa