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 ↓


Plastics and polymers


Plastics and polymers are essential materials in our modern world. They are present in almost every aspect of our everyday lives, from packaging and clothing to cars and electronics. But what exactly are plastics and polymers and why are they so important? Let's explore these fascinating materials in more detail.

What are polymers?

A polymer is a large molecule made up of repeating smaller units called monomers. Think of a polymer as a long chain, with each link in the chain representing a monomer. When these monomers join together, they form a polymer.

Example of polymer

Imagine a paperclip chain. Each paperclip is a monomer, and when you connect the paperclips together, you create a chain, which represents a polymer.

Polymers can have different properties depending on the type of monomers used and their arrangement. Some polymers are flexible, like rubber bands, while others are rigid, like the plastic case of a laptop.

Monomer + Monomer + Monomer + ... = Polymer

Types of polymers

Polymers may be classified into two main types:

Synthetic polymers

Synthetic polymers are man-made. They are produced through chemical processes. Examples include plastic bags, bottles, and synthetic rubber.

Natural polymers

Natural polymers are found in nature. They are not made by humans. Examples include DNA, proteins, and cellulose, which is found in plants.

What are plastics?

Plastic is a type of synthetic polymer. They are made from natural materials such as cellulose, oil, natural gas, coal, and salt through a process called polymerization.

During polymerization, monomers chemically bond together to form long chains, forming the plastic materials we use. This process allows manufacturers to produce different types of plastics with different characteristics.

Properties of plastics

Plastic has many beneficial properties, including:

  • Light weight: Plastic is generally lighter than metal or glass.
  • Durability: Plastics are durable and resistant to environmental conditions.
  • Malleability: Plastics can be moulded into various shapes.
  • Insulation: They insulate from electricity and heat.

Types of plastic

Thermoplastics

These plastics can be melted and transformed many times. Common examples include polyethylene used in grocery bags and PVC used in pipes.

Thermosetting plastics

These plastics can only be molded once. Once solidified, they cannot be melted again. An example of this is Bakelite, which is used in electrical insulators.

Polymerization process

Polymerization is a chemical process in which small molecules called monomers combine together to form a polymer. This can happen in several ways. There are two main types of polymerization:

Addition polymerization

In this method, the monomers attach to each other without losing any of the other molecules. Imagine sticking Lego blocks together without any of them falling off.

H2C=CH2 + H2C=CH2 + ... = -[CH2-CH2]-n (Ethylene to Polyethylene)

Condensation polymerization

In this method, monomers join together by losing small molecules such as water. This is similar to forming a chain by gluing the ends of paper strips and cutting off small overlaps.

HO-CH2-CH2-OH + HOOC-CH2-COOH = -[OCH2CH2OOCCH2COO]-

Daily uses of plastic

It's hard to imagine a world without plastic. Here are some everyday uses:

  • Packaging: Plastics are widely used in the packaging of food, beverages and other goods.
  • Automotive: Car parts are often made of plastic because it is lightweight yet strong.
  • Clothing: Synthetic fibers such as polyester and nylon are types of plastic.
  • Electronics: Many electronic devices have a casing made of plastic.

Environmental impact and recycling

Plastic is useful, but it is also a challenge for the environment. Plastic can take hundreds of years to decompose, causing pollution. Recycling is an important process for managing plastic waste.

Recycling process

Recycling involves collecting used plastics, cleaning them, and processing them to make new products. This reduces the need to produce new plastics and also reduces harm to the environment.

The importance of reducing plastic use

It is important to reduce plastic use by choosing reusable products and supporting innovations in biodegradable plastics.

Biodegradable and bioplastic

Biodegradable plastics break down naturally over time, reducing the impact they have on the environment. Bioplastics are made from renewable resources such as corn starch, making them a sustainable option.

Conclusion: The future of plastics and polymers

Plastics and polymers are an integral part of modern life, offering convenience and versatility. However, responsible management through recycling and innovations in biodegradable materials are essential for a sustainable future.

Studying plastics and polymers helps us understand the science behind everyday materials and prepares us to make informed choices for a healthy planet.


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