- A homologous series is a group of compounds with the same functional group and similar chemical properties.
- Successive members differ by one CH₂ (methylene) unit, increasing the molecular mass by 14 u.
- All members of a homologous series follow the same general molecular formula (e.g., alkanes CnH2n+2).
- Physical properties such as boiling and melting points show a gradual change with increasing molecular mass.
- Knowing the properties of a few members helps predict the properties of other members in the series.
Topics
Gravitation
- Concept of Gravitation
- Force and Motion
- Centripetal Force
- Kepler’s Laws
- Law of Orbit or Kepler's First Law
- Law of Areas or Kepler's Second Law
- Law of Periods or Kepler's Third Law
- Newton's Universal Law of Gravitation
- Uniform Circular Motion (UCM)
- Earth’s Gravitational Force
- Earth’s Gravitational Acceleration
- Mass and Weight
- Gravitational Waves
- Free Fall
- Gravitational Potential Energy
- Escape Velocity
- Weightlessness in Space
Periodic Classification of Elements
- Classification of Elements
- Dobereiner’s Triads
- Newland's Law of Octaves
- Mendeleev’s Periodic Table
- Insights into Mendeleev’s Periodic Table
- Modern Periodic Law
- The Modern Periodic Table
- Structure of the Modern Periodic Table
- Modern Periodic Table and Electronic Configuration of Elements
- Groups and Electronic Configuration
- Periods and Electronic Configuration
- Periodic Trends in the Modern Periodic Table
- Atomic Size
- Metallic and Non-metallic Characters
- Gradation in Halogen Family
Chemical Reactions and Equations
- Chemical Reaction
- Chemical Equations
- Balancing Chemical Equation
- Types of Chemical Reactions > Combination Reaction
- Types of Chemical Reactions > Decomposition Reaction
- Types of Chemical Reactions > Single Displacement Reaction
- Types of Chemical Reactions > Double Displacement Reaction
- Endothermic and Exothermic Processes
- Rate of Chemical Reaction
- Factors Affecting the Rate of a Chemical Reaction
- Chemical Properties of Carbon Compounds > Oxidation
- Chemical Properties of Carbon Compounds > Reduction
- Corrosion of Metals
- Rancidity
Effects of Electric Current
- Electric Circuit
- Heating Effect of Electric Current
- Introduction to Magnetic Effect of Current
- Right-hand Thumb Rule
- Applications of Biot-Savart's Law > Magnetic Field at the Axis of a Circular Current-carrying Loop
- Applications of Ampere’s Circuital Law > Magnetic Field of a Long Straight Solenoid
- Force on a Current-Carrying Conductor Placed in a Uniform Magnetic Field
- Fleming’s Left Hand Rule
- Electric Motor
- Electromagnetic Induction
- Galvanometer
- Faraday's Laws of Electromagnetic Induction
- Fleming’s Right Hand Rule
- Alternating current (AC) and Direct Current (DC)
- Electric Generator
Heat
Refraction of Light
Lenses
- Concept of Lenses
- Images Formed by Convex Lenses
- Images Formed by Concave Lenses
- Sign Convention
- Lens Formula
- Magnification
- Power of a Lens
- Combination of Lenses
- Defects of Vision and Their Corrections > Myopia
- Defects of Vision and Their Corrections > Hypermetropia
- Defects of Vision and Their Corrections > Presbyopia
- Apparent Size of an Object
- Use of Concave Lenses
- Use of Convex Lenses
- Persistence of Vision
Metallurgy
- Physical Properties of Metals
- Physical Properties of Non-metal
- Chemical Properties of Metal
- Reactions of Metals
- Reactivity Series of Metals
- Chemical Properties of Non-metal
- Ionic Compounds
- Metallurgy
- Basic Principles of Metallurgy > Concentration of Ores
- Basic Principles of Metallurgy > Extraction of Metals
- Basic Principles of Metallurgy > Refining of Metals
- Corrosion of Metals
- Prevention of Corrosion
Carbon Compounds
- Bonds in Carbon Compounds
- Carbon: A Versatile Element
- Hydrocarbons
- Straight chains, Branched chains, and Rings of Carbon atoms
- Functional Groups in Carbon Compounds
- Homologous Series
- Nomenclature
- Chemical Properties of Carbon Compounds > Combustion
- Chemical Properties of Carbon Compounds > Oxidation
- Chemical Properties of Carbon Compounds > Addition Reaction
- Chemical Properties of Carbon Compounds > Substitution Reaction
- Ethanol
- Ethanoic Acid
- Macromolecules and Polymers
Space Missions
School of Elements
The Magic of Chemical Reactions
- Chemical Equations
- Types of Chemical Reactions > Combination Reaction
- Types of Chemical Reactions > Decomposition Reaction
- Types of Chemical Reactions > Single Displacement Reaction
- Types of Chemical Reactions > Double Displacement Reaction
- Chemical Properties of Carbon Compounds > Oxidation
- Types of Double Displacement: Neutralization Reaction
The Acid Base Chemistry
- Properties of Acids > Physical Properties
- The pH Scale
- Acids, Bases and Their Reactivity
- Acid or a Base in a Water Solution
- Preparation and Uses of Baking Soda
- Preparation and Uses of Bleaching Powder
- Preparation and Uses of Washing Soda
- Preparation and Uses of Plaster of Paris
- Chemicals from Common Salt - Soap as a Salt
The Electric Spark
All about Electromagnetism
- Magnetic force
- Bar Magnet and Solenoid Analogy
- Right-hand Thumb Rule
- Applications of Biot-Savart's Law > Magnetic Field at the Axis of a Circular Current-carrying Loop
- Applications of Ampere’s Circuital Law > Magnetic Field of a Long Straight Solenoid
- Force on a Current-Carrying Conductor Placed in a Uniform Magnetic Field
- Electric Motor
- Electromagnetic Induction
- A.C. Generator
- Simple D.C. Motor
- Household Electrical Circuits
Wonders of Light 1
Wonders of Light 2
Striving for better Environment 1
- Abatement of Pollution
- Sustainable Use of Resources
Estimated time: 14 minutes
- Definition: Homologous Series
- Key Points: Homologous Series
Maharashtra State Board: Class 10
Homologous Series in Organic Chemistry
A homologous series is a group of organic compounds having the same functional group and similar chemical properties but differing in the length of the carbon chain. Each successive member differs by a -CH₂- unit and has a molecular mass increase of 14 u.
Characteristics of a Homologous Series:
- Regular Addition of CH₂ Units: Each successive compound differs by one -CH₂- unit.
- Gradation in Physical Properties: Physical properties (e.g., boiling points) show a gradual increase or decrease along the series.
- Similar Chemical Properties: All members have the same functional group, leading to similar chemical reactions.
- General Molecular Formula: Members of the series can be represented by a single general formula.
General Formula for Homologous Series:
Alkanes: CₙH₂ₙ₊₂, where n = 1 for the first member (Methane: CH₄).
Alkenes: CₙH₂ₙ, where n = 2 for the first member (Ethene: C₂H₄).
Alkynes: CₙH₂ₙ₋₂, substituting n = 2, 3, 4:
- 1st Member: Ethyne (C₂H₂)
- 2nd Member: Propyne (C₃H₄)
- 3rd Member: Butyne (C₄H₆)
Maharashtra State Board: Class 10
Examples of Homologous Series
(a) Homologous Series of Alkanes
General formula: CₙH₂ₙ₊₂
First member: Methane (CH₄) (n = 1)
| Name | Molecular Formula | Condensed Structural Formula | No. of Carbon Atoms | No. of -CH₂- Units | Boiling Point (°C) |
|---|---|---|---|---|---|
| Methane | CH₄ | CH₄ | 1 | - | -162 |
| Ethane | C₂H₆ | CH₃-CH₃ | 2 | 1 | -88.5 |
| Propane | C₃H₈ | CH₃-CH₂-CH₃ | 3 | 2 | -42 |
| Butane | C₄H₁₀ | CH₃-CH₂-CH₂-CH₃ | 4 | 3 | 0 |
| Pentane | C₅H₁₂ | CH₃-CH₂-CH₂-CH₂-CH₃ | 5 | 4 | 36 |
(b) Homologous Series of Alcohols
General formula: CₙH₂ₙ₊₁OH
| Name | Molecular Formula | Condensed Structural Formula | No. of Carbon Atoms | No. of -CH₂- Units | Boiling Point (°C) |
|---|---|---|---|---|---|
| Methanol | CH₄O | CH₃-OH | 1 | 1 | 63 |
| Ethanol | C₂H₆O | CH₃-CH₂-OH | 2 | 2 | 78 |
| Propanol | C₃H₈O | CH₃-CH₂-CH₂-OH | 3 | 3 | 97 |
| Butanol | C₄H₁₀O | CH₃-CH₂-CH₂-CH₂-OH | 4 | 4 | 118 |
(c) Homologous Series of Alkenes
General formula: CₙH₂ₙ
| Name | Molecular Formula | Condensed Structural Formula | No. of Carbon Atoms | No. of -CH₂- Units | Boiling Point (°C) |
|---|---|---|---|---|---|
| Ethene | C₂H₄ | CH₂=CH₂ | 2 | - | -102 |
| Propene | C₃H₆ | CH₃-CH=CH₂ | 3 | 1 | -48 |
| 1-Butene | C₄H₈ | CH₃-CH₂-CH=CH₂ | 4 | 2 | -6.5 |
| 1-Pentene | C₅H₁₀ | CH₃-CH₂-CH₂-CH=CH₂ | 5 | 3 | 30 |
CBSE: Class 10
Maharashtra State Board: Class 10
CISCE: Class 10
Maharashtra State Board: Class 10
CISCE: Class 10
Definition: Homologous Series
The same functional group substitutes for hydrogen in a carbon chain is called a homologous series.
OR
A homologous series is a group of organic compounds having similar structure and similar chemical properties in which the successive compounds differ by a CH2 group.
OR
The series of compounds formed by joining the same functional group in the place of a particular hydrogen atom on the chains having sequentially increasing length is called homologous series.
CBSE: Class 12
Maharashtra State Board: Class 10
CISCE: Class 10
Maharashtra State Board: Class 10
CISCE: Class 10
