Grade 8
  1. Introduction to Chemistry  1.1. Nature and scope of chemistry  1.2. Importance of chemistry in daily life  1.3. Chemistry and its relation with other sciences  1.4. The role of chemistry in industry, medicine and the environment  1.5. Scientific investigation and experimental methods in chemistry
  2. Matter and its properties  2.1. Definition and classification of matter  2.2. Physical and chemical properties of matter  2.3. Law of conservation of matter  2.4. Extensive and Intensive Properties of Matter  2.5. Kinetic molecular theory of matter  2.6. States of matter: solids, liquids, gases, plasmas, and Bose-Einstein condensates  2.7. Changes in state and energy are involved  2.8. Diffusion and Brownian motion
  3. Elements, Compounds, and Mixtures  3.1. Definition and differences between elements, compounds, and mixtures  3.2. Atomic Structure and Atomic Number  3.3. Chemical symbols and formulas  3.4. Trends in the Periodic Table (Groups and Periods)  3.5. Classification of Elements: Metals, Nonmetals and Metalloids  3.6. Rare Earth Elements and Transition Metals  3.7. Types of mixtures: homogeneous and heterogeneous  3.8. Separation of Mixtures Using Physical and Chemical Methods
  4. Separation Techniques  4.1. Filtration, Sedimentation and Decantation  4.2. Evaporation and crystallization  4.3. Distillation and Fractional Distillation  4.4. Chromatography and its applications  4.5. Sublimation in the purification of compounds  4.6. The role of centrifugation in biochemical processes
  5. Atomic Structure  5.1. Dalton's atomic theory  5.2. Structure of the atom: protons, neutrons and electrons  5.3. Bohr's atomic model  5.4. Introduction to Quantum Mechanical Model  5.5. Electron Configuration and Energy Levels  5.6. Excitation and emission spectra  5.7. Isotopes and their applications
  6. Periodic Table and Chemical Trends  6.1. History and Development of the Periodic Table  6.2. Modern periodic law  6.3. Periodicity and trends in atomic and ionic sizes  6.4. Ionization Energy, Electron Affinity and Electronegativity  6.5. Introduction to Lanthanides and Actinides  6.6. Application of periodic trends in chemistry
  7. Chemical Bonding and Molecular Structure  7.1. Types of chemical bonds: ionic, covalent and metallic bonds  7.3. Polar and Nonpolar Molecules  7.4. Hydrogen bonding and its applications  7.5. Intermolecular forces: dipole-dipole, London dispersion force
  8. Chemical Reactions and Stoichiometry  8.1. Chemical Equations and Balance  8.2. Types of Chemical Reactions: Combination, Decomposition, Displacement and Redox  8.3. Introduction to stoichiometry and the mole concept  8.4. Limiting reactant in chemical equations  8.5. Reaction rate, catalyst, and factors affecting reaction rate
  9. Acids, Bases and Salts  9.1. Definition and Properties of Acids and Bases  9.2. Strong vs. Weak Acids and Bases  9.3. pH Scale and pH Calculation  9.4. Neutralization reactions  9.5. Buffer solutions and their importance  9.6. Applications of Acids, Bases and Salts in Daily Life
  10. Solutions and Solubility  10.1. Definition of Solution, Solute, and Solvent  10.2. Factors Affecting Solubility  10.3. Concentration units: molarity and molality  10.4. Saturated, unsaturated and supersaturated solutions  10.5. Concept of osmosis and reverse osmosis  10.6. Concentrative properties of solutions
  11. Gases and Gas Laws  11.1. Properties of gases  11.2. Introduction to Ideal and Real Gases  11.3. Boyle's Law, Charles' Law and Avogadro's Law  11.4. Ideal Gas Equation and Its Applications  11.5. Application of Gas Laws in Real Life
  12. Thermochemistry and energy transformation  12.1. Energy in Chemical Reactions  12.2. Exothermic vs. Endothermic Reactions  12.3. Heat and Enthalpy Changes  12.4. Calorimetry and heat transfer in reactions
  13. Metals and Nonmetals  13.1. Physical and Chemical Properties of Metals and Nonmetals  13.2. Reactivity Series of Metals  13.3. Corrosion and its prevention  13.4. Extraction of metals from ores  13.5. Uses of metals and non-metals in daily life
  14. Introduction to Organic Chemistry  14.1. Characteristics of carbon and organic compounds  14.2. Functional groups and their importance  14.3. Simple Hydrocarbons: Alkenes, Alkenes and Alkynes  14.4. Isomerism in organic compounds  14.5. Introduction to polymers and their uses
  15. Environmental Chemistry and Sustainability  15.1. Green Chemistry Principles  15.2. Effects of Chemical Pollution on Ecosystems  15.3. Acid rain and its effects  15.4. Ozone layer depletion and global warming  15.5. Waste Management and Recycling in Chemistry

Grade 8 → Introduction to Organic Chemistry ↓


Introduction to polymers and their uses


Have you ever wondered why some substances stretch like rubber bands while others are hard and brittle like glass? Or why some plastics can be molded into toys, bottles, or even car parts? The answer lies in a fascinating part of chemistry called polymers. This section will go into depth about what polymers are, how they are made, and how they affect our daily lives. We'll explore some text and visual examples to help you understand these amazing substances.

What are polymers?

Polymers are large molecules that are made by linking together many smaller units called monomers. Imagine the polymer as a long chain, and each link in the chain as a monomer. Just like many beads are linked together to form a bracelet, polymers are made by linking together many monomers.

 |---|---|---|---|---| H - C - C - C - C - C - H | | | | | | HHHHHH

The above code structure shows a polymer chain where each unit is a monomer. Monomers are like building blocks that can vary in structure and type, forming different types of polymers.

How are polymers made?

Polymers are formed through chemical reactions called polymerizations. There are two main types of polymerization: addition polymerization and condensation polymerization.

Addition polymerization

In addition polymerization, monomers join together without losing any atoms. This type of polymerization usually involves monomers with double or triple bonds. A common example of this is the creation of polyethylene, a plastic used to make bags and bottles.

 n CH₂=CH₂ → -(CH₂-CH₂)n-

The equation shows ethylene (CH₂=CH₂) being converted into polyethylene (-(CH₂-CH₂)n-), where n represents the number of repeating units.

Condensation polymerization

In condensation polymerization, monomers join together with the loss of smaller molecules such as water or methanol. A well-known example of this is the manufacture of nylon, which is used in making clothing.

 HOOC-(CH₂)₄-COOH + H₂N-(CH₂)₆-NH₂ → [-OC-(CH₂)₄-CO-NH-(CH₂)₆-NH-]n + 2n H₂O

Here, carboxylic acid monomers and amine monomers react to form a polymer and release water.

Types of polymers

Polymers are classified into natural, synthetic, and semi-synthetic polymers depending on their origin and structure.

Natural polymers

Natural polymers are found in nature. Examples include proteins, cellulose, and rubber.

Protein: found in our hair, nails, muscles; made up of amino acid monomers.
Cellulose: Found in plants; made of glucose monomers.
Natural rubber: It is obtained from rubber trees; composed of isoprene monomers.

Synthetic polymers

Synthetic polymers are man-made. Examples include plastic, nylon, and polyester.

Plastic: Made from petrochemicals; used in packaging, containers.
Nylon: Used in clothing, ropes; known for strength and flexibility.
Polyester: Used in clothing; known for its wrinkle resistance and durability.

Semi-synthetic polymers

These are derived from natural polymers and processed to enhance properties. An example of this is rayon made from cellulose.

Rayon: Used in the textile industry, resembling silk; processed from natural cellulose.

Uses of polymers

Polymers are incredibly versatile and are found in many applications. Let's take a look at some everyday examples:

Household items

Polymers are present everywhere in our homes. Plastics such as polyethylene and polypropylene are used in containers, buckets, and packaging materials.

Clothing

Clothing materials such as polyester, nylon, and acrylic are made from polymers. These materials are lightweight, wrinkle-resistant, and durable.

Electronics

Polymers are vital in electronics. They are used as insulating materials and components in devices such as smartphones and computers.

Automotive industry

Cars and airplanes use polymers in their bodies and interiors to reduce weight and increase fuel efficiency.

Medicine

In the medical field, polymers are used to make implants, sutures, and drug delivery systems. Biodegradable polymers help create environmentally friendly medical disposables.

Visual example

Let's imagine what polymers might look like. Below are some simple diagrams:

The above view shows the chain of monomer units that make up the polymer.

This view shows how monomers are joined by bonds to form a long polymer chain.

As we have discovered, polymers are incredible materials with a wide variety of forms and functions. Whether from natural or synthetic sources, polymers are constantly innovating and making a significant impact in a variety of industries and in our everyday lives. This introduction to polymers is just the beginning of understanding the complex and essential world of chemistry.


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