Grade 9
  1. Mechanics  1.1. Motion  1.1.1. Types of motion  1.1.2. Distance and displacement  1.1.3. Speed and Velocity  1.1.4. Acceleration  1.1.5. Graphical representation of motion  1.1.6. Equations of motion  1.1.7. Uniform and non-uniform motion  1.1.8. Free fall and acceleration due to gravity  1.1.9. Relative speed  1.1.10. Circular motion  1.2. Laws of force and motion  1.2.1. The concept of force  1.2.2. newton's first law of motion  1.2.3. Newton's second law of motion  1.2.4. Newton's third law of motion  1.2.5. Inertia and types of inertia  1.2.6. Motion  1.2.7. Conservation of momentum  1.2.8. Application of Newton's laws in daily life  1.2.9. Types of Forces (Contact and Non-Contact)  1.2.10. Friction and its effects  1.3. Gravitational force  1.3.1. Newton's law of universal gravitation  1.3.2. Importance of Gravitational Force  1.3.3. Acceleration due to gravity  1.3.4. Free fall and weightlessness  1.3.5. Mass and weight  1.3.6. Variation of g with height and depth  1.3.7. Kepler's laws of planetary motion  1.3.8. Satellites and their orbits  1.4. Work, Energy and Power  1.4.1. Concept of work  1.4.2. Positive and negative actions  1.4.3. Work done by constant and variable force  1.4.4. Energy and its forms  1.4.5. Kinetic energy and potential energy  1.4.6. Law of conservation of energy  1.4.8. Commercial unit of energy  1.4.9. Work–energy theorem  1.5. Simple machines  1.5.1. Types of simple machines  1.5.2. Mechanical advantage  1.5.3. Machine efficiency  1.5.4. Levers and their types  1.5.5. Pulleys and Inclined Planes  1.5.6. Gears and their uses
  2. Properties of matter  2.1. States of matter  2.1.1. Solids, liquids and gases  2.1.2. Properties of different states of matter  2.1.3. Change in state of matter  2.1.4. Plasma and Bose–Einstein condensate  2.2. Density and pressure  2.2.1. Concept of density and relative density  2.2.2. Pressure in solids, liquids and gases  2.2.3. Pascal's law and its applications  2.2.4. Atmospheric pressure and its variations  2.2.5. Surface tension and capillarity  2.3. Buoyancy and Archimedes' principle  2.3.1. Buoyant force  2.3.2. Archimedes principle  2.3.3. Applications of Archimedes' Principle  2.3.4. floating and sinking objects  2.3.5. Theory of Flotation and Archimedes' Principle
  3. Heat and Thermodynamics  3.1. Temperature and heat  3.1.1. Concept of heat and temperature  3.1.2. Temperature measurement  3.1.3. Temperature scales  3.2. Heat transfer  3.2.1. Conduction of heat  3.2.2. Convection of heat  3.2.3. heat radiation  3.2.4. Applications of heat transfer  3.2.5. Thermal conductivity  3.3. Thermal expansion  3.3.1. Expansion of solids, liquids and gases  3.3.2. Abnormal expansion of water  3.3.3. Applications of Thermal Expansion  3.4. Specific heat capacity and latent heat  3.4.1. Concept of specific heat capacity  3.4.2. Measurement and applications of specific heat  3.4.3. Latent heat of fusion and vaporization  3.4.4. Heat Engines and Efficiency
  4. Waves and sound  4.1. Waves and their types  4.1.1. Mechanical and electromagnetic waves  4.1.2. Longitudinal and Transverse Waves  4.1.3. Properties of Waves  4.1.4. Wavelength, frequency and speed of the wave  4.1.5. Superimposition of waves  4.2. Sound waves  4.2.1. Nature and transmission of sound  4.2.2. Speed of sound in different mediums  4.2.3. Reflection of sound and echo  4.2.4. Sonar and ultrasound  4.2.5. Resonance and pulsation  4.3. Sound characteristics  4.3.1. Intensity, loudness and quality of sound  4.3.2. Doppler effect in sound
  5. Lighting and Optics  5.1. Reflection of light  5.1.1. Laws of reflection  5.1.2. Reflection from a plane mirror  5.1.3. Reflection from a spherical mirror  5.1.4. Image formation by concave and convex mirrors  5.1.5. Applications of Reflection  5.2. Refraction of light  5.2.1. Laws of refraction  5.2.2. Refractive index  5.2.3. Refraction through a glass slab  5.2.4. Refraction in water and air  5.2.5. Lenses and their types  5.2.6. Image formation by convex and concave lenses  5.2.7. Total internal reflection and its applications  5.3. Dispersion and scattering of light  5.3.1. Spectrum of white light  5.3.2. Prisms and Dispersion  5.3.3. Tyndall effect and blue sky
  6. Electricity and Magnetism  6.1. Electric charge and static electricity  6.1.1. The concept of electric charge  6.1.2. Charging by friction, contact and induction  6.1.3. Electroscope and its working  6.2. Current Electricity  6.2.1. The concept of electric current  6.2.2. Ohm's Law and Resistance  6.2.3. Factors affecting resistance  6.2.4. Series and Parallel Circuits  6.2.5. Heating effect of electric current  6.2.6. Electric power and energy  6.3. Magnetism  6.3.1. Natural and artificial magnets  6.3.2. Properties of magnets  6.3.3. Earth's magnetism  6.3.4. Magnetic field and field lines  6.3.5. Electromagnets and their applications
  7. Modern Physics  7.1. structure of the atom  7.1.1. Atomic Structure and Subatomic Particles  7.1.2. Electrons, Protons, and Neutrons  7.1.3. Rutherford and Bohr model  7.2. Radioactivity  7.2.1. Types of radioactive emissions  7.2.2. Half-life and radioactive decay  7.2.3. Uses and Hazards of Radioactivity
  8. Space science and astronomy  8.1. The universe and its components  8.1.1. Stars and galaxies  8.1.2. Planets and Solar System  8.2. Satellites  8.2.1. Natural and artificial satellites  8.2.2. Use of satellites

Grade 9 → Properties of matter → States of matter ↓


Change in state of matter


Matter is everything that occupies space and has mass. It exists in various states, mainly solid, liquid and gas. Understanding how matter changes from one state to another helps to understand how the physical world works. These changes are mainly driven by external factors such as temperature and pressure.

Basic states of matter

Solids

Solids have a definite shape and volume. The particles in solids are packed very closely together and vibrate in fixed positions. This tightly packed structure means that solids do not change their shape easily.

Liquids

Liquids have a definite volume but no definite shape. They take the shape of their container. Particles in a liquid are adjacent to each other but can slide over each other, allowing the liquid to flow.

Gases

Gases have neither a definite shape nor a definite volume. They expand to fill their container. The particles in gases are far apart and move freely at high speeds.

Changing states of matter

Matter changes from one state to another when energy is added or removed. These changes usually involve heat or pressure. When energy is added, particles move faster. When energy is removed, particles slow down.

1. Melting

Melting is the process in which a solid substance turns into a liquid. This happens when the solid substance gains so much energy (heat) that its particles move out of their fixed positions and start moving around each other. An everyday example of melting is ice turning into water. Below is a visual example to understand the concept of melting:

        -------------------- (Solid. Tightly packed particles) | | | | | | -------------------- After gaining energy: (~ ~ ~ ~ ~ ~ ~ ~ ~ ~) (Liquid. Particles loosely packed) ~ ~ ~ ~ ~ ~

2. Cold

Freezing is the opposite of melting. It is the process in which a liquid turns into a solid. When the liquid loses energy, the motion of the particles slows down, and they begin to arrange themselves in a certain position to form a solid. Water turning into ice is an example of freezing.

        (~ ~ ~ ~ ~ ~ ~ ~ ~ ~) (Liquid. Particles loosely packed) ~ ~ ~ ~ ~ ~ After losing energy: -------------------- (Solid. Tightly packed particles) | | | | | | --------------------

3. Evaporation

Vaporization is the process of a liquid changing into a gas. There are two types of vaporization: evaporation and boiling.

Evaporation

Evaporation is a slow process that occurs at the surface of a liquid, where the molecules on the surface gain enough energy to be released into the gaseous state. The liquid does not have to be at boiling point for this to happen. An example of evaporation is the slow drying up of puddles of water after rain.

Boil

Boiling is the rapid vaporization that occurs throughout a liquid at its boiling point. Water boiling at 100 °C (212 °F) at normal atmospheric pressure is a visual example of this process.

4. Condensation

Condensation is the process of a gas changing into a liquid. It occurs when a gas loses enough energy, causing its particles to slow down and move closer together to form a liquid. An everyday example of this is the formation of water droplets on the outside of a glass of cold beverage.

5. Sublimation

Sublimation is an interesting process in which a solid substance changes directly into a gas without going through the liquid state. It occurs when the particles of a solid substance gain enough energy to overcome both their fixed positions and the attraction between them. A common example of sublimation is dry ice (solid carbon dioxide) transforming directly into carbon dioxide gas. To understand this, imagine:

        -------------------- (Solid. Tightly packed particles) | | | | | | -------------------- After gaining energy: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ (Gas. Particles widely spaced) ~ ~ ~ ~ ~ ~

6. Deposition

Deposition is the opposite of sublimation, where a gas changes directly into a solid without first becoming a liquid. It occurs when gas particles rapidly lose energy, causing them to slow down enough to form a solid structure. Frost that forms on a cold surface overnight is an example of deposition.

Factors affecting state change

Several factors can influence the change in the states of matter:

Temperature

Temperature plays an important role in phase changes. Higher temperatures give particles more energy, making them move faster, which can lead to changes such as melting or evaporation. Conversely, lowering the temperature removes energy from the particles, slowing them down and potentially leading to freezing or condensation.

Pressure

Pressure affects the state of matter by changing the distance between particles. Increasing pressure can bring particles closer together, leading to changes such as gas to liquid or liquid to solid. Decreasing pressure can cause particles to move farther apart, leading to changes such as liquid to gas.

Real life applications of state changes

Refrigeration

Refrigeration uses the principles of evaporation and condensation to cool the air. The refrigerant absorbs heat by evaporating inside the coils, then releases the absorbed heat by condensing outside the coils. This cycle cools the interior of the refrigerator.

Air conditioning

Air conditioning uses the same principles as refrigeration, but on a larger scale. It uses refrigerants to cool buildings by absorbing heat from indoors and releasing it outside.

Industrial drying

Many industries use controlled evaporation to remove excess moisture from products. Understanding and controlling evaporation is important in processes such as grain or paint drying.

Power generation

Power plants often rely on heating water to create steam. This steam drives turbines, which produce electricity, illustrating the use of state changes in energy production.

Food preservation

Freezing and dehydration are food preservation techniques that both involve changing the state of matter to extend the shelf life of perishable goods.

Conclusion

The study of changes in the state of matter is important in understanding natural phenomena and practical applications in technology and industry. The key is that these changes are caused primarily by energy variations, usually in the form of heat, which affect the motion and arrangement of particles in matter. Mastering this subject provides a strong foundation for further exploration in physics and chemistry and gives insights into the workings of the physical world.


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Change in state of matter

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