Grade 12
  1. Solid state  1.1. Classification of solids  1.2. Crystal Lattice and Unit Cell  1.3. Packing Efficiency  1.4. Density of unit cell  1.5. Imperfections in solids (point and line defects)  1.6. Electrical Properties of Solids (Conductors, Insulators and Semiconductors)  1.7. Magnetic Properties of Solids (Diamagnetic, Paramagnetic and Ferromagnetic Materials)
  2. Solution  2.1. Types of Solutions (Homogeneous and Heterogeneous)  2.2. Expressing concentration of solutions (mass %, volume %, molarity, molality, normality, mole fraction)  2.3. Solubility of solids and gases in liquids (Henry's law)  2.4. Raoult's Law and Ideal and Non-Ideal Solutions  2.5. Syndrome properties  2.6. Abnormal molar mass and Van't Hoff factor
  3. Electrochemistry  3.1. Electrochemical cells (galvanic and electrolytic cells)  3.2. Galvanic cell and EMF of the cell  3.3. Standard electrode potential and electrochemical series  3.4. Nernst equation and its applications  3.5. Conductivity and electrolytic cells (specific, molar and equivalent conductivity)  3.6. Kohlrausch's law and its applications  3.7. Batteries (primary and secondary cells)  3.8. Corrosion and its prevention
  4. Chemical kinetics  4.1. Rate of chemical reaction  4.2. Factors affecting the reaction rate (concentration, temperature, catalyst, surface area)  4.3. Order and molecularity of the reaction  4.4. Integrated Rate Equations (Zero, First and Second Order)  4.5. Half-life of a reaction  4.6. Collision theory and activation energy  4.7. Arrhenius equation and its applications
  5. Surface chemistry  5.1. Adsorption and its types (Physicosorption and Chemisorption)  5.2. Catalysis and its types (homogeneous and heterogeneous)  5.3. Colloids and their properties (Tyndall effect, Brownian motion, coagulation)  5.4. Emulsions and gels  5.5. Applications of Colloids
  6. General principles and processes of separation of elements  6.1. Presence of metals and minerals  6.2. Concentration of ores (gravity separation, froth flotation, magnetic separation)  6.3. Extraction of raw metals (roasting, calcination, reduction)  6.4. Thermodynamic and electrochemical principles of metallurgy  6.5. Refining of metals
  7. P-block elements  7.1. Group 15 elements (nitrogen and phosphorus)  7.2. Group 16 Elements (Oxygen, Sulphur and their Compounds)  7.3. Group 17 Elements (Halogens and their Compounds)  7.4. Group 18 Elements  7.5. Properties and Trends in p-Block Elements  7.6. Important compounds of p-block elements (ammonia, phosphine, sulphuric acid, hydrochloric acid)  7.7. Interhalogen compounds and their applications
  8. d-block and f-block elements  8.1. General Properties of Transition Metals  8.2. Properties of Inner Transition Metals (Lanthanoids and Actinoids)  8.3. Lanthanoid and actinoid contractions  8.4. Coordination Chemistry of d-Block Elements
  9. Coordination compounds  9.1. Werner's theory and modern concepts  9.2. Coordination number and type of ligand  9.3. Nomenclature of Coordination Compounds  9.4. Isomerism (geometrical and optical) in coordination compounds  9.5. Bonding in Coordination Compounds (Valence Bond Theory and Crystal Field Theory)  9.6. Stability and applications of coordination compounds in medicine and industry
  10. Haloalkanes and haloarenes  10.1. Classification and nomenclature of haloalkanes and haloarenes  10.2. Physical and Chemical Properties of Haloalkanes and Haloarenes  10.3. Mechanism of Nucleophilic Substitution Reactions (SN1 and SN2)  10.4. Uses and environmental effects (ozone depletion, CFCs)
  11. Alcohol, phenol and ether  11.1. Structure and classification of alcohols, phenols and ethers  11.2. Preparation and properties of alcohols  11.3. Preparation and properties of phenol  11.4. Preparation and properties of ethers  11.5. Chemical Reactions and Uses
  12. Aldehydes, ketones and carboxylic acids  12.1. Structure and nomenclature in aldehydes, ketones and carboxylic acids  12.2. Preparation and properties of aldehydes and ketones  12.3. Chemical reactions in aldehydes, ketones and carboxylic acids (nucleophilic addition, oxidation and reduction)  12.4. Preparation and Properties of Carboxylic Acids  12.5. Chemical Reactions and Uses of Carboxylic Acids
  13. Nitrogen-containing organic compounds  13.1. Amines (classification, structure, basicity)  13.2. Preparation and properties of amines  13.3. Reactions of Amines (Diazotization, Carbylamine Reaction)  13.4. Diazonium salts and their applications in paint industry
  14.1. Carbohydrates (classification and properties)  14.2. Proteins (Structure and Function)  14.3. Enzymes (Mechanism and Function)  14.4. Nucleic acids (DNA and RNA)  14.5. Vitamins and hormones
  15. Polymer  15.1. Classification of Polymers (Addition, Condensation, Copolymers)  15.2. Types of polymerization (free radical, ionic, condensation)  15.3. Important Polymers and Their Uses  15.4. Biodegradable and non-biodegradable polymers
  16. Chemistry in Everyday Life  16.1. Drugs and their classification (analgesics, antipyretics, antibiotics, antacids)  16.2. Chemicals in food and cosmetics (preservatives, artificial sweeteners, antioxidants)  16.3. Cleaning agents and detergents (soaps, synthetic detergents, surfactants)  16.4. Environmental Chemistry (Pollution, Green Chemistry, Sustainable Chemistry)

Grade 12 → Solid state ↓


Electrical Properties of Solids (Conductors, Insulators and Semiconductors)


Solids are characterized by a definite structure where the particles are very closely bound to each other. Among the diverse properties of solids, their electrical properties are of vital importance. In this article, we will discuss the electrical properties of three primary types of solids: conductors, insulators, and semiconductors. We will explore examples to better understand their characteristics, the principles behind their functions, and their applications in the real world.

Conductor

Conductors are materials that allow the free flow of electrical charge, usually in the form of electrons. The most common conductors are metals such as copper, silver, and aluminum. When an electric field is applied, the electrons in the conductor begin to move, producing an electric current.

Theory of conductors

The main reason electric current flows in conductors is the presence of free electrons. In metal conductors, the outer electrons are loosely bound to the atom, forming what is known as an "electron cloud". These electrons can move freely throughout the lattice in response to an electric field, causing current to flow. This is explained by the free electron model:

Electrons in metal = free electrons ≈ electron cloud

Visualization of conductors

Consider a simple illustration of a metal mesh in a conducting wire:

Metal ions free electrons

Examples of conductors

  • Copper (Cu): It is known for its excellent conductivity and is commonly used in electrical wiring.
  • Silver (Ag): It has the highest electrical conductivity of any element.
  • Aluminum (Al): Used in power lines because it is lightweight and relatively good conductor.

Insulator

Insulators are materials that prevent or substantially reduce the flow of electrical charges. They are often used to protect us from unexpected electrical shocks and to restrict the flow of current to the desired paths in electrical circuits.

The principle of the insulator

The electrons in insulators are tightly bound to their atoms and are unable to move freely under the influence of an electric field. As a result, the materials do not conduct electricity effectively. This can be attributed to the large energy gap (>3 eV) between the valence band and the conduction band:

Energy gap (ΔE) > 3 eV → Insulator

Visualization of insulators

Consider a simple illustration of the atomic structure of an insulator:

Atoms

Examples of insulators

  • Rubber: Commonly used in insulating gloves and boots for electrical work.
  • Glass: Used in insulators for high voltage power lines.
  • Plastic: This is often used to coat wires and cables.

Semiconductors

Semiconductors have electrical properties that fall between conductors and insulators. They have a moderate energy band gap (~1 eV) and their conductivity can be easily manipulated by impurities (doping) or external conditions such as temperature or light.

Theory of semiconductors

Semiconductors have a smaller energy gap between the valence and conduction bands than insulators. At absolute zero, they behave like insulators, but at high temperatures or when energy is provided, electrons can jump into the conduction band, allowing current to flow.

Energy gap (ΔE) ≈ 1 eV → Semiconductor

Types of semiconductors

Semiconductors can be classified into two main types:

  • Intrinsic semiconductors: Pure without any impurities. Example: Silicon (Si).
  • Extrinsic semiconductors: impurities are added to modify the conductivity. These are further divided into:
    • N-type: The extra electrons contribute to conduction. Example: Phosphorous-doped silicon.
    • P-type: holes contribute to conduction. Example: boron-doped silicon.

Visualization of semiconductors

Consider a simple illustration of an intrinsic semiconductor:

Silicon atom

Examples of semiconductors

  • Silicon (Si): Widely used in electronic devices such as computers and smartphones.
  • Germanium (Ge): Used in transistors and diodes.
  • Gallium arsenide (GaAs): Used in high-speed and optoelectronic components.

Application

Each type of solid has different applications depending on its electrical properties:

  • Conductors: Used in electrical wiring and connections.
  • Insulators: Used in coating of electrical wires and as insulators in electronics.
  • Semiconductors: Important in the manufacture of electronic components such as transistors, diodes, and solar cells.

Conclusion

Understanding the electrical properties of conductors, insulators and semiconductors is fundamental in the design and application of various electrical and electronic systems. As technology advances, these materials play a vital role in the innovations that shape our modern world.


Grade 12 → 1.6


U
username
0%
completed in Grade 12

← Prev (1.5)
Imperfections in solids (point and line defects)
Next (1.7) →
Magnetic Properties of Solids (Diamagnetic, Paramagnetic and Ferromagnetic Materials)

Comments 



Electrical Properties of Solids (Conductors, Insulators and Semiconductors)

https://www.chemistryelite.com/g12/1.6?ceal=en