Grade 10
  1. Matter and its properties  1.1. States of matter  1.2. Physical and chemical properties of matter  1.3. Classification of substances (elements, compounds, mixtures)  1.4. Changes in Matter (Physical and Chemical Changes)  1.5. Law of conservation of mass and law of definite proportions
  2. Atomic Structure  2.1. Historical development of the atomic model  2.2. Subatomic particles (protons, neutrons, electrons)  2.3. Atomic number, mass number and isotopes  2.4. Electronic Configuration and Energy Levels  2.5. Valency, ion formation and oxidation state
  3. Periodic table  3.1. History and Development of the Periodic Table  3.2. Modern Periodic Law and Periodic Trends  3.3. Groups and Periods in the Periodic Table  3.4. Trends in the Periodic Table  3.5. Metals, non-metals, metalloids and their properties  3.6. Noble gases and their chemical inertness
  4. Chemical bond  4.1. Formation of Chemical Bonds (Octet Rule)  4.2. Ionic Bonding and Properties of Ionic Compounds  4.3. Covalent Bond and Properties of Covalent Compounds  4.4. Metallic bond and its properties  4.5. Molecular geometry and VSEPR theory  4.6. Polarity and dipole moment of molecules  4.7. Intermolecular forces
  5. Chemical Reactions and Equations  5.1. Types of Chemical Reactions  5.2. Writing and balancing chemical equations  5.3. Law of conservation of mass in chemical reactions  5.4. Factors Affecting Chemical Reactions  5.5. Catalysts and their role in chemical reactions  5.6. Exothermic and Endothermic Reactions
  6. Stoichiometry and Chemical Calculations  6.1. Mole concept and Avogadro number  6.2. Molar Mass and Gram-Mole Conversions  6.3. Empirical and molecular formula  6.4. Stoichiometric calculations and chemical yield  6.5. Limiting and Excess Reactants
  7. Acids, Bases and Salts  7.1. Properties and Definitions of Acids and Bases (Arrhenius, Bronsted-Lowry, Lewis)  7.2. pH Scale, pOH, and Indicators  7.3. Neutralization reactions and salt formation  7.4. Strength of Acids and Bases (Strong vs. Weak Acids and Bases)  7.5. Common Acids and Bases in Daily Life  7.6. Salts, their solubility and applications
  8. Metals and Nonmetals  8.1. Physical and chemical properties of metals  8.2. Physical and Chemical Properties of Non-Metals  8.3. Reactivity Series of Metals and Displacement Reactions  8.4. Extraction of metals from ores  8.5. Corrosion, its causes and prevention  8.6. Alloys, their composition and uses
  9. Carbon and its compounds  9.1. Allotropes of Carbon  9.2. Hydrocarbons and their classification (alkanes, alkenes, alkynes)  9.3. Functional groups in organic compounds  9.4. Nomenclature of organic compounds (IUPAC system)  9.5. Isomerism in organic chemistry (structural and geometrical)  9.6. Important organic reactions (combustion, addition, substitution, polymerization)  9.7. Applications of organic compounds in industry and daily life
  10. Environmental Chemistry  10.1. Air Pollution (Sources, Effects and Control)  10.2. Water Pollution (Causes, Effects and Remedies)  10.3. Greenhouse effect and global warming  10.4. Ozone layer depletion and its effects  10.5. Green Chemistry and Its Applications  10.6. sustainable chemistry practice
  11. Thermochemistry  11.1. Heat and Energy Changes in Chemical Reactions  11.2. Exothermic and Endothermic Reactions  11.3. Enthalpy, enthalpy change, and heat of reaction  11.4. Specific heat capacity and calorimetry  11.5. Energy Changes in Combustion Reactions
  12. Electrochemistry  12.1. Electrolytes and non-electrolytes  12.2. Electrolysis and its applications (electroplating, extraction of metals)  12.3. Redox reactions (oxidation and reduction)  12.4. Galvanic cell and electrochemical series  12.5. Corrosion and electrochemical prevention methods
  13. Chemical kinetics and equilibrium  13.1. Rate of chemical reactions and its measurement  13.2. Factors affecting the reaction rate (catalyst, temperature, concentration)  13.3. Reversible and irreversible reactions  13.4. Dynamic equilibrium and equilibrium constant  13.5. Le Chatelier's principle and its applications
  14. Gases and Gas Laws  14.1. Properties of gases and kinetic molecular theory  14.2. Boyle's Law (Pressure-Volume Relation)  14.3. Charles's Law  14.4. Gay-Lussac's Law  14.5. Combined Gas Law and Ideal Gas Law  14.6. Real Gases vs Ideal Gases
  15. Nuclear Chemistry  15.1. Introduction to Radioactivity and Nuclear Reactions  15.2. Types of radioactive decay (alpha, beta, gamma)  15.3. Half-life and applications of radioactive isotopes  15.4. Nuclear fission and fusion reactions  15.5. Nuclear power generation and its environmental impact

Grade 10 → Carbon and its compounds ↓


Hydrocarbons and their classification (alkanes, alkenes, alkynes)


Hydrocarbons are organic compounds that consist of only hydrogen and carbon atoms. They are the simplest form of organic compounds and can be found abundantly in nature, especially in fossil fuels such as natural gas, oil, and coal. The study of hydrocarbons is a fundamental part of chemistry, as these compounds form the basis of organic chemistry.

Classification of hydrocarbons

Hydrocarbons can be classified into several types depending on their structure and bonding. The main classes are:

  • Hydrocarbons
  • Alkene
  • Alkynes
  • Aromatic hydrocarbons

This discussion will focus on the first three, known as aliphatic hydrocarbons.

Hydrocarbons

Alkanes, sometimes called paraffins, are the simplest family of hydrocarbons. They contain only single bonds and are saturated hydrocarbons, meaning they have the maximum number of hydrogen atoms attached to each carbon atom. The general formula for alkanes is C n H 2n+2.

Alkanes have different chain lengths and can form different structures, but they all follow the same basic formula. Here are some examples of simple alkanes:

  • Methane (CH4)
  • Ethane (C 2 H 6)
  • Propane (C 3 H 8)
  • Butane (C4H10)

Structure and bonding in alkenes

Alkenes have a tetrahedral geometry around each carbon atom, which means that each carbon atom forms four single covalent bonds with hydrogen or other carbon atoms. This is due to sp 3 hybridization of orbitals.

         HH
         ,
    HCCH
         ,
         HH

In the above diagram of ethane, each line represents a single bond between atoms.

C C

This simplified diagram shows the structure of ethane, where two carbon atoms are bonded by a single bond.

Naming of alkenes

Naming alkanes involves identifying the longest chain of carbon atoms and naming the branches. The International Union of Pure and Applied Chemistry (IUPAC) naming rules are used:

  1. Find the longest continuous chain of carbon atoms and give it a suitable alkane name.
  2. Identify and name any branches or side chains.
  3. Number the chain from the end closest to the branch.
  4. Combine the names, including the status of each branch.

For example, in 2-methylpentane, the main chain has five carbons (pentane), with a methyl group on the second carbon.

Alkene

Alkanes are hydrocarbons that contain at least one carbon-carbon double bond. They are unsaturated hydrocarbons because they can accommodate more hydrogen atoms by breaking the double bond. The general formula of an alkane is C n H 2n.

Examples include:

  • Ethene (C 2 H 4)
  • Propane (C 3 H 6)
  • Butane (C4H8)

Structure and bonding in alkynes

In alkenes, the presence of a double bond means that the carbon atoms involved are sp 2 hybridised, resulting in a planar structure around the double bond.

         H
          ,
          C = C
          ,
         HH

The above structure represents ethene.

C C

Nomenclature of alkenes

The naming of alkenes follows the same rules as for alkenes, but must indicate the position of the double bond:

  1. Identify the longest chain that contains a double bond.
  2. Number the chain from the end closest to the double bond.
  3. Include the position of the double bond in the name.

For example, 1-butene indicates a 4-carbon chain with a double bond between the first and second carbons.

Alkynes

Alkynes contain at least one carbon-carbon triple bond, which also makes them unsaturated hydrocarbons with the ability to add more hydrogen. The general formula is C n H 2n-2.

Some examples of alkynes include:

  • Ethene (C 2 H 2), commonly known as acetylene
  • Propine (C 3 H 4)
  • Butane (C 4 H 6)

Structure and bonding in alkynes

The triple bond in alkynes consists of one sigma bond and two pi bonds, and the carbon atoms are sp hybridized, giving a linear geometry.

          HC≡CH

This is the simplest alkyne, known as acetylene.

C C

Naming of alkynes

The nomenclature of alkynes involves indicating the position of the triple bond in the carbon chain:

  1. Identify the longest carbon chain that contains a triple bond.
  2. Number the chain starting from the end nearest to the triple bond.
  3. Include the position of the triple bond in the name.

For example, 1-butyne indicates a 4-carbon chain with a triple bond between the first and second carbons.

Properties of hydrocarbons

Physical properties

Hydrocarbons exhibit a variety of physical properties depending on their structure:

  • Boiling point and melting point: As molecular weight increases, the boiling point and melting point generally increase because of greater van der Waals forces.
  • Solubility: Hydrocarbons are generally nonpolar and insoluble in water, but may dissolve in nonpolar solvents such as hexane.
  • Density: Hydrocarbons are less dense than water, which is why oil floats on water.

Chemical properties

Chemical reactivity differs between alkenes, alkene, and alkynes:

  • Alkenes: Relatively unreactive due to the strength of C-C and C-H bonds. They undergo combustion and substitution reactions.
  • Alkenes and alkynes: Are more reactive due to the presence of double and triple bonds. They undergo addition reactions, where atoms get added to the carbon involved in the multiple bonds.

Use of hydrocarbons

Hydrocarbons have a wide variety of applications. They are the primary components of fuels such as petrol, diesel, and natural gas. Alkanes serve as the basis for lubricants and the starting materials for many other synthetic compounds. Alkenes are important in the production of polymers such as polyethylene, while alkynes are used in welding and the synthesis of other chemical compounds.

Conclusion

Understanding the fundamentals of hydrocarbons and their classification into alkanes, alkenes, and alkynes provides foundational knowledge for further studies in organic chemistry. Recognizing variations in structure and bonding provides information about their physical and chemical properties and their wide applications in real-world scenarios.


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Allotropes of Carbon
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Hydrocarbons and their classification (alkanes, alkenes, alkynes)

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