Grade 6
  1. Introduction to Chemistry  1.1. What is Chemistry?  1.2. Importance of chemistry in daily life  1.3. Branches of chemistry  1.4. Safety rules in chemistry laboratory  1.5. Common Laboratory Equipment and Their Uses
  2. Matter and its states  2.1. Definition of Matter  2.2. Properties of matter  2.3. States of matter  2.4. Solid state  2.5. Fluid state  2.6. Gaseous state  2.7. Plasma state  2.8. Changes in the states of matter  2.9. Melting and freezing  2.10. Evaporation and Condensation  2.11. Sublimation  2.12. Deposit
  3. Physical and chemical changes  3.1. Definition of Physical Change  3.2. Examples of physical change  3.3. Definition of Chemical Change  3.4. Examples of chemical change  3.5. Difference Between Physical and Chemical Changes  3.6. Indicators of Chemical Change
  4. Elements, Compounds, and Mixtures  4.1. Definition of the element  4.2. Classification of elements  4.3. Metals  4.4. Non metallic  4.5. Metalloids  4.6. Noble gases  4.7. Definition of compound  4.8. Properties of Compounds  4.9. Definition of Mixture  4.10. Types of mixtures  4.11. Homogeneous mixture  4.12. Heterogeneous mixtures
  5. Separation of mixtures  5.1. The need for isolation  5.2. Separation methods  5.3. Handpicking and winnowing  5.4. Filtration  5.5. Sedimentation and decantation  5.6. Evaporation  5.7. Crystallization  5.8. Distillation  5.9. Magnetic Separation  5.10. Chromatography
  6. Air and its composition  6.1. Components of air  6.2. Importance of Oxygen  6.3. The importance of nitrogen in the air and its composition  6.4. Carbon dioxide in the atmosphere  6.5. The role of water vapor and other gases in air and its composition  6.6. Properties of Air  6.7. Uses of air  6.8. Air pollution and its effects
  7. Water and its properties  7.1. Importance of Water  7.2. Sources of water  7.3. Properties of water  7.4. Water as the universal solvent  7.5. Water Purification  7.6. Water purification methods (boiling, filtration, chlorination)  7.7. Water cycle  7.8. Water conservation  7.9. Water pollution and its effects
  8. Acids, Bases and Salts  8.1. Definition of Acid  8.2. Properties of Acids  8.3. Examples of Acids  8.4. Definition of Bases  8.5. Properties of bases  8.6. Examples of Bases  8.7. Definition of Salt  8.8. Neutralization reaction  8.9. pH Scale and Indicators  8.10. Uses of Acids, Bases and Salts
  9. Introduction to the Periodic Table  9.1. History of the Periodic Table  9.2. Arrangement of elements in the periodic table  9.3. Groups and periods  9.4. Importance of periodic table  9.5. First 10 elements and their symbols
  10. Metals and Nonmetals  10.1. Properties of Metals  10.2. Properties of Non-Metals  10.3. Difference Between Metals and Nonmetals  10.4. Uses of metals and nonmetals  10.5. Corrosion of metals and its prevention
  11. chemical reactions  11.1. Introduction to Chemical Reactions  11.2. Types of Chemical Reactions  11.3. combustion reaction  11.4. Oxidation and Reduction  11.5. Simple chemical equations  11.6. Rusting of iron
  12. Fuel and energy  12.1. Types of fuel  12.2. Fossil fuels  12.3. Renewable and non-renewable sources of energy  12.4. Energy Conservation  12.5. Alternative sources of energy (solar, wind, hydropower)
  13. Plastic and fiber  13.1. Natural and synthetic fibers  13.2. Properties of plastics  13.3. Advantages and disadvantages of plastic  13.4. Recycling of plastic  13.5. Biodegradable and non-biodegradable materials

Grade 6 → Matter and its states ↓


Changes in the states of matter


Matter is anything that occupies space and has mass. Everything around us is made of matter. Matter comes in different forms, which we call states. The most common states of matter are solid, liquid, and gas. Sometimes matter can also be in a state called plasma, such as in stars and lightning.

Changes in the states of matter refer to changes from one state to another. These changes usually involve the addition or removal of energy, such as heat. As you learn about these changes, you will understand how heat can cause matter to transform and behave differently.

Solid to liquid: melting

When a solid changes into a liquid, the process is called melting. Melting occurs when the particles of the solid gain enough energy to move out of their fixed positions. This is usually achieved by raising the temperature by applying heat.

Example:

Think of ice turning into water. Place a piece of ice in a bowl at room temperature. As the ice absorbs heat, it melts and becomes water.

Solid (ice) Liquid (water) melting

Liquid to solid: freezing

When a liquid turns into a solid, the process is called solidification. During solidification, the particles in the liquid lose energy, usually due to heat loss, they slow down and assume fixed positions to form a solid.

Example:

Freezing is the process of water turning into ice. If you put water in an ice tray in the freezer, it will lose heat and become solid ice.

Liquid (water) Solid (ice) solidify

Liquid to gas: evaporation and boiling

When a liquid turns into a gas, the process is called evaporation or boiling. Evaporation occurs at any temperature when the particles on the surface of the liquid gain enough energy to become a gas. When the liquid reaches a certain temperature, called the boiling point, the entire liquid boils.

Example:

Water in a vessel placed on the stove boils and turns into steam, which is a gas. This is called boiling.

When you leave a puddle of water on the ground, over time it evaporates and disappears into the air.

Liquid (water) Gas (steam)

Gas to liquid: condensation

When a gas changes back into a liquid, the process is called condensation. During condensation, gas particles lose energy, slow down, and stick together to become a liquid.

Example:

When you breathe on a cold window, the water vapor from your breath condenses into tiny droplets, forming a mist on the glass.

Gas (steam) Liquid (water)

Solid to gas: sublimation

Sublimation is the process in which a solid substance changes directly into a gas without first changing into a liquid. It occurs under specific conditions where the particles gain enough energy to be released directly into the gaseous state.

Example:

Dry ice sublimes to form carbon dioxide gas. You may have seen dry ice used in fog machines for special effects. It turns directly from a solid to a gas.

Solid (dry ice) Gas (CO2)

Gas to solid: deposition

Deposition is the opposite of sublimation. It occurs when a gas changes directly into a solid. It happens when gas particles lose energy so quickly that they don't have time to become a liquid first.

Example:

Frost forms on a cold surface when water vapour present in the air condenses overnight into a solid form on the cold surface.

Gas (water vapor) Solid (frosted)

Understanding energy transformation

Every change in the state of matter involves an energy transformation. In melting and boiling, energy is absorbed by the particles. This energy is used to break the bonds holding them in a particular state. In contrast, processes such as condensation and freezing release energy, usually in the form of heat.

The energy required or released in these processes is known as latent heat. For example, the latent heat of fusion is the heat absorbed by a solid to become a liquid at the melting point, and the latent heat of vaporization is the heat absorbed by a liquid to become a gas at the boiling point.

H 2 O(solid) + heat → H 2 O(liquid)
H 2 O(liquid) + heat → H 2 O(gas)
H 2 O(gas) → H 2 O(liquid) + heat
H 2 O(liquid) → H 2 O(solid) + heat

Understanding how these changes occur not only helps in understanding fundamental science concepts but also helps in recognizing their applications in daily life, such as refrigeration, cooking and even weather phenomena.

Conclusion

Changes in the states of matter are essential to understanding the physical changes that occur in our natural world and technological processes. Recognizing these changes helps us understand how energy is involved in creating and maintaining different states of matter. Whether observing water cycles in nature or developing modern refrigeration systems, this knowledge adds to our understanding of the universe around us.


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Changes in the states of matter

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