Grade 7
  1. Introduction to Chemistry  1.1. What is Chemistry?  1.2. Importance of chemistry in daily life  1.3. Branches of chemistry  1.4. Scientific Method in Chemistry  1.5. Laboratory Safety Rules and Precautions  1.6. Common Laboratory Equipment and Their Uses  1.7. Units of measurement in chemistry
  2. Matter and its properties  2.1. Definition of Matter  2.2. Classification of matter  2.3. Properties of matter  2.3.1. Physical properties  2.3.2. Chemical properties  2.4. States of matter  2.4.1. Solid state  2.4.2. Fluid state  2.4.3. Gaseous state  2.4.4. Plasma and Bose–Einstein condensates  2.5. Changes in the states of matter  2.5.1. Melting and freezing  2.5.2. Evaporation and Condensation  2.5.3. Sublimation and deposition  2.6. Density and its applications  2.7. Diffusion and its importance
  3. Elements, Compounds, and Mixtures  3.1. Definition of the element  3.2. Classification of elements  3.3. Metals, Nonmetals and Metalloids  3.4. Noble gases and their properties  3.5. Introduction to the Periodic Table  3.6. Definition of Compound  3.7. Properties of Compounds  3.8. Introduction to Chemical Formulas  3.9. Definition of Mixture  3.10. Types of mixtures  3.10.1. Homogeneous mixture  3.10.2. Heterogeneous mixtures  3.11. Difference Between Compounds and Mixtures  3.12. Solutions, Colloids and Suspensions
  4. Separation of mixtures  4.1. Need for separation of mixtures  4.2. Separation methods  4.2.1. Filtration  4.2.2. Sedimentation and decantation  4.2.3. Evaporation  4.2.4. Crystallization  4.2.5. Distillation  4.2.6. Chromatography  4.2.7. Magnetic Separation  4.2.8. Centrifugation
  5. Atomic Structure  5.1. Introduction to Atoms  5.2. Structure of the atom  5.2.1. Nucleus and electron cloud  5.3. Subatomic particles  5.3.1. Proton  5.3.2. Neutron  5.3.3. Electrons  5.4. Atomic number and mass number  5.5. Isotopes and their uses  5.6. Ions and ion formation
  6. Periodic table  6.1. Introduction to the Periodic Table  6.2. Groups and periods  6.3. Trends in the Periodic Table  6.3.1. Atomic Size  6.3.2. Metallic and non-metallic character  6.3.3. Electronegativity  6.3.4. Reactivity of the elements  6.4. Alkali metals and their properties
  7. Chemical bond  7.1. Why do atoms form bonds?  7.2. Types of chemical bonds  7.2.1. Ionic bond  7.2.2. Covalent bond  7.2.3. Metal Bond  7.3. Properties of Ionic and Covalent Compounds  7.4. Intermolecular forces
  8. Chemical reactions  8.1. Introduction to Chemical Reactions  8.2. Signs of a chemical reaction  8.3. Types of Chemical Reactions  8.3.1. Combination Reactions  8.3.2. Decomposition reactions  8.3.3. Displacement reactions  8.3.4. Double displacement reactions  8.3.5. Combustion reactions  8.4. Law of conservation of mass  8.5. Balancing simple chemical equations
  9. Acids, Bases and Salts  9.1. Definition of Acid and Base  9.2. Properties of Acids  9.3. Properties of bases  9.4. pH Scale and Indicators  9.5. Neutralization reactions  9.6. Common Acids and Bases in Everyday Life  9.7. Preparation and use of salts  9.8. Strong and weak acids and bases
  10. Solutions and Solubility  10.1. Definition of Solution  10.2. Components of the solution  10.2.1. Solvent  10.2.2. solute  10.3. Factors Affecting Solubility  10.4. Concentration of solutions  10.5. Saturated and unsaturated solutions  10.6. Colloids and suspensions  10.7. Solubility curve and its interpretation
  11. Air and atmosphere  11.1. Composition of air  11.2. Properties of gases in the air  11.3. Importance of Oxygen and Carbon Dioxide  11.4. Air pollution and its effects  11.5. Greenhouse effect and global warming  11.6. Ways to reduce air pollution  11.7. Ozone layer and its importance
  12. Water and its importance  12.1. Properties of Water  12.2. Water as the universal solvent  12.3. Importance of water for life  12.4. Water pollution and its effects  12.5. Water Purification  12.5.1. Filtration  12.5.2. boil  12.5.3. Chlorination in water purification  12.5.4. reverse osmosis  12.6. Hard and soft water  12.7. Water cycle and its importance
  13. Fuel and energy  13.1. Types of fuel  13.1.1. Fossil fuels  13.1.2. Renewable energy sources  13.2. Combustion and energy release  13.3. Global warming and its effects  13.4. Alternative sources of energy  13.5. Ways to conserve energy
  14. Metals and Nonmetals  14.1. Physical and chemical properties of metals  14.2. Physical and Chemical Properties of Non-Metals  14.3. Difference Between Metals and Nonmetals  14.4. Uses of metals and nonmetals  14.5. Corrosion of metals and its prevention  14.6. Alloys and their importance
  15. Plastics and polymers  15.1. Natural and synthetic polymers  15.2. Properties of plastics  15.3. Biodegradable and Non-Biodegradable Plastics  15.4. Environmental impact of plastic  15.5. Recycling and waste management in plastics and polymers  15.6. Daily Uses of Polymers
  16. Introduction to Organic Chemistry  16.1. Basic definitions of organic chemistry  16.2. Carbon Compounds in Daily Life  16.3. Hydrocarbons  16.4. Simple functional groups (alcohols and carboxylic acids)  16.5. Importance of organic compounds in industry

Grade 7 → Matter and its properties → Properties of matter ↓


Physical properties


Matter surrounds us everywhere. Everything you see, touch or feel is made of matter. In Grade 7 Chemistry, one of the major topics we study is "Properties of Matter". Of these, "Physical Properties" are fundamental. They allow us to identify, describe and distinguish between different types of matter without changing the chemical identity of the object. Understanding physical properties gives us information about the characteristics and classification of matter in our world.

What are physical properties?

Physical properties define characteristics that can be seen or measured without causing any change in the matter. These include properties such as colour, odour, density, melting point, boiling point, and state of matter (solid, liquid, gas). These properties are important because they help us identify and classify different types of materials.

Examples of physical properties

Let us understand some common physical properties with real life examples:

1. Colour

Colour is one of the most obvious physical properties. It is the way we visually perceive different substances. For example, gold appears yellow and shiny, while silver is bright and white. Plants are usually green because of chlorophyll. The colour of a substance can often give us an initial clue to its identity.

This red circle can visually represent an object with a color property.

2. Smell

Smell is another physical property that is important in identifying substances. Think of the pungent smell of vinegar or the fresh scent of orange peel. The presence of certain molecules in the air that interact with our olfactory system helps us perceive these odors.

3. Density

Density is defined as mass per unit volume. It is a measure of how dense a substance is. For example, lead is very dense, which means it feels heavy for its size, while Styrofoam is less dense, which feels light and airy. Density can be calculated using the formula:

Density = Mass / Volume

4. Melting point

The melting point is the temperature at which a substance changes from a solid to a liquid. It is a characteristic property for identifying substances. For example, ice melts at 0°C to become water, while the melting point of gold is about 1,064°C.

5. Boiling point

The boiling point is the temperature at which a liquid turns into a gas. For example, water boils at 100°C at sea level. The boiling point can vary depending on the atmospheric pressure.

6. State of matter

The state of matter is a property that indicates whether a substance is solid, liquid, or gas at a given temperature and pressure. Ice is the solid state of water, water itself is a liquid, and steam is the gaseous state. Let's explain this concept with a diagram.

In this diagram, the rectangle represents a solid, the circle represents a liquid, and the intersected lines represent a gas.

7. Rigidity

Hardness is a measure of how resistant a material is to shape change when a force is applied. Diamonds are known for their hardness and are considered the hardest natural material.

8. Glitter

Luster describes how a substance reflects light. Metals such as gold and silver have lustre, while non-metals such as sulfur have a dull lustre.

9. Solubility

Solubility is the ability of a substance to dissolve in another substance, usually a liquid. Salt dissolving in water is a classic example demonstrating solubility. Sugar also dissolves in water, which emphasizes the importance of this property in everyday life.

Why it is important to understand physical properties

Understanding physical properties serves several purposes:

  • They help in the classification and identification of unknown substances.
  • Provide scientists and engineers with critical information to understand how materials will behave in particular environments or applications.
  • Innovation and materials play a key role in development, as each property determines how the material can be used.

Closing thoughts

The physical properties of matter, as seen, describe various aspects of matter that do not change its basic identity. As students of chemistry, recognizing these properties enables a deeper understanding of the world of matter and its underlying nature. From everyday items like water and salt to precious metals like gold, these properties provide clues about characteristics and potential uses. Science continues to use these properties as a springboard for innovation and discovery in advancing technology and improving our understanding of the world around us.


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Physical properties

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