Grade 11
  1. Basic concepts of chemistry  1.1. Importance of Chemistry  1.2. Nature and scope of chemistry  1.3. laws of chemical combination  1.3.1. Law of conservation of mass  1.3.2. Law of definite proportions  1.3.3. Law of multiple proportions  1.3.4. Law of gaseous volume  1.3.5. Avogadro's Law  1.4. Dalton's atomic theory  1.5. Mole concept and molar mass  1.6. Percent composition  1.7. Empirical and molecular formula  1.8. Stoichiometry and Stoichiometric Calculations  1.9. Limiting reagent concept
  2. Structure of the atom  2.1. Discovery of the electron, proton, and neutron  2.2. Atomic Model  2.2.1. Thomson's model  2.2.2. Rutherford's model  2.2.3. Bohr's model  2.3. Quantum mechanical model of the atom  2.4. Dual nature of matter and radiation  2.5. Heisenberg's uncertainty principle  2.6. Quantum numbers  2.7. Atomic orbitals and their shapes  2.8. Electronic configuration of elements  2.9. Aufbau principle  2.10. Pauli's exclusion principle  2.11. Hund's maximum multiplicity rule  2.12. de Broglie's hypothesis  2.13. Photoelectric effect
  3. Classification of elements and periodicity in properties  3.1. Historical development of the periodic table  3.2. Modern Periodic Law and Periodic Table  3.3. Periodic trends in properties  3.3.1. Atomic and Ionic Radius  3.3.2. Ionization enthalpy  3.3.3. Electron gain enthalpy  3.3.4. Electronegativity  3.3.5. Valency  3.3.6. Metallic and Non-Metallic Properties  3.3.7. Oxidation states  3.4. Unusual Properties of the First Elements
  4. Chemical Bonding and Molecular Structure  4.1. Kossel–Lewis approach to chemical bonding  4.2. Ionic or electrovalent bond  4.3. Covalent bond and its features  4.4. Bond parameters  4.5. VSEPR Theory  4.6. Valence bond theory  4.7. Hybridization and its types  4.8. Molecular orbital theory  4.8.1. Bond order and stability  4.9. Hydrogen bonding
  5. States of matter  5.1. Intermolecular forces  5.2. Gas Laws  5.2.1. Boyle's law  5.2.2. Charles's Law  5.2.3. Avogadro's Law  5.2.4. Dalton's law of partial pressure  5.2.5. Graham's law of spread  5.3. Ideal Gas Equation and Applications  5.4. Real gases and deviations from ideal behaviour  5.5. Kinetic molecular theory of gases  5.6. Liquefaction of gases  5.7. Properties of Liquids  5.8. Surface tension and viscosity
  6. Thermodynamics  6.1. System and environment  6.2. Types of systems in thermodynamics  6.3. Types of procedures  6.4. First law of thermodynamics  6.5. Internal energy and enthalpy  6.6. Heat capacity and specific heat  6.7. Hess's law of constant heat summation  6.8. Bond dissociation enthalpy  6.9. Enthalpy of formation and combustion  6.10. Enthalpy of solution and neutralization  6.11. Spontaneity and the second law of thermodynamics  6.12. Gibbs free energy and its applications
  7. Balance  7.1. The concept of balance  7.2. Equilibrium constant and its applications  7.3. Le Chatelier's principle  7.4. Ionic equilibrium in solutions  7.5. Acid and Base Theory  7.5.1. Arrhenius concept  7.5.2. Bronsted-Lowry concept  7.5.3. Lewis concept  7.6. pH Scale and pOH  7.7. Common ion effect  7.8. Hydrolysis of salts  7.9. Buffer solutions and their mechanism of action  7.10. Solubility equilibrium of sparingly soluble salts
  8. Redox reactions  8.1. Oxidation and reduction concepts  8.2. Oxidation number and its applications  8.3. Redox reactions in terms of electron transfer  8.4. Balancing redox reactions (oxidation number and ion-electron methods)  8.5. Types of redox reactions  8.6. Electrochemical Cells and Redox Reactions
  9. Hydrogen  9.1. Position of Hydrogen in the Periodic Table  9.2. Isotopes of hydrogen  9.3. Preparation of Hydrogen  9.4. Properties of Hydrogen  9.5. Hydrides and their classification  9.6. Water and heavy water  9.7. Hydrogen peroxide and its properties  9.8. Uses of Hydrogen and Its Compounds
  10. S-block elements (alkali and alkaline earth metals)  10.1. Group 1 Elements - Properties and Trends  10.2. Group 2 Elements - Properties and Trends  10.3. Unusual properties of lithium and beryllium  10.4. Important compounds of sodium and their uses  10.5. Important Compounds of Magnesium and Calcium
  11. Some p-block elements  11.1. General Introduction to p-Block Elements  11.2. Group 13 Elements  11.2.1. Boron and its compounds  11.3. Group 14 Elements  11.3.1. Carbon and its allotropes  11.3.2. Important Compounds of Carbon and Silicon
  12. Organic Chemistry - Some Basic Principles and Techniques  12.1. Classification and Nomenclature of Organic Compounds  12.2. Structural representation of organic compounds  12.3. Classification of organic reactions  12.4. Electronic Effects in Organic Chemistry  12.4.1. Inductive effect  12.4.2. Resonance effect  12.4.3. Hyperconjugation  12.5. Reaction mechanism and intermediate species  12.6. Purification and qualitative analysis of organic compounds
  13. Hydrocarbons  13.1. Hydrocarbons  13.1.1. Preparation and Properties of Alkenes  13.2. alkene  13.2.1. Preparation and Properties of Alkenes  13.2.2. Electrophilic addition reactions  13.3. Alkynes  13.3.1. Preparation and Properties of Alkynes  13.4. Aromatic hydrocarbons  13.4.1. Structure and properties of benzene  13.4.2. Electrophilic substitution reactions of benzene
  14. Environmental Chemistry  14.1. Environmental Pollution  14.2. Atmospheric pollution and the greenhouse effect  14.3. Water pollution and treatment methods  14.4. Soil pollution and its effects  14.5. Industrial waste and its treatment  14.6. Strategies for pollution control

Grade 11 → Hydrocarbons ↓


Hydrocarbons


Alkanes are a fundamental group of hydrocarbons. Hydrocarbons are organic compounds that consist entirely of hydrogen and carbon atoms. Among the different types of hydrocarbons, alkanes are the simplest. They are also known as saturated hydrocarbons because they contain single bonds connecting all the carbon atoms. This simple structure is one of the reasons why they serve as the backbone for many chemical compounds and are involved in numerous chemical reactions.

Structure of alkenes

The general formula for an alkane is C n H 2n+2. This formula reflects the fact that for any integer n there are n carbon atoms and 2n + 2 hydrogen atoms. The simplest alkane is methane, composed of one carbon atom and four hydrogen atoms, represented as CH 4.

Let's imagine some alkenes:

Methane (CH4)

The simplest alkane, containing one carbon atom and four hydrogen atoms.

H | H — C — H | H

Ethane (C 2 H 6)

It consists of two carbon atoms and six hydrogen atoms:

HH | | H — C — C — H | | HH

Propane (C 3 H 8)

It consists of three carbon atoms and eight hydrogen atoms:

HHH | | | H — C — C — C — H | | | HHH

Properties of alkenes

Alkanes are known to have unique physical and chemical properties. Physically, they are generally nonpolar molecules because they have an even distribution of charge. Due to this nonpolarity, alkanes are insoluble in water but soluble in organic solvents such as hexane or ether.

Alkanes have relatively low boiling points compared to other organic compounds of similar size. The boiling point of alkanes increases as the number of carbon atoms increases. This trend is attributed to the increase in van der Waals forces with the increase in the size of the molecule.

In addition, branched alkanes have lower boiling points than their straight-chain isomers with the same number of carbon atoms. This is because being branched reduces the surface area available for van der Waals interactions.

Chemical reactions of alkenes

Alkanes participate in a wide variety of chemical reactions, although they are generally less reactive than other types of hydrocarbons because of their stable C–C and C–H bonds. Some common reactions involving alkanes are as follows:

Combustion

Alkanes burn easily, reacting with oxygen to form carbon dioxide, water, and energy. This reaction is highly exothermic and is the basis for their use as fuel.

C n H 2n+2 + (3n+1)/2 O 2 → n CO 2 + (n+1) H 2 O

Substitution reaction

Alkanes can undergo substitution reactions with halogens in the presence of UV light, which corresponds to a reaction in which one or more hydrogen atoms are replaced by halogen atoms.

CH 4 + Cl 2 → CH 3 Cl + HCl

Isomerism in alkenes

Isomerism is a fascinating concept in the field of chemistry, where compounds with the same formula have different structural arrangements. In alkanes, isomerism occurs primarily in hydrocarbons with four or more carbon atoms. For example, butane (C 4 H 10) can exist as two different structural isomers:

  • n-butane - a straight-chain structure.
  • Isobutane - a branched-chain structure.

n-butane (C4H10)

HHHH | | | | H — C — C — C — C — H | | | | HHHH

Isobutane (C4H10)

H | H — C — H | | H — C — H | H

Naming of alkenes

The International Union of Pure and Applied Chemistry (IUPAC) nomenclature system provides systematic guidelines for naming alkanes. Each alkane is named based on the number of carbon atoms it contains followed by the suffix '-en'. Some basic alkanes and their names are as follows:

  • Methane: C1
  • Ethane: C2
  • Propane: C3
  • Butane: C4
  • Pentane: C5
  • Hexane: C6
  • Heptane: C7
  • Octane: C 8
  • Nonane: C9
  • Decane: C10

For more complex alkenes with branched structures, the substituents (or side groups) are named and numbered to indicate their position on the main carbon chain. The longest continuous chain of carbon atoms determines the base name of the compound. Numbers are assigned starting from the nearest end of the carbon chain to ensure the fewest possible numbers for substituent locations.

Production and applications of alkenes

Alkanes are typically extracted from natural sources such as petroleum and natural gas. The refining process involves separating and converting components of crude oil to produce various hydrocarbon compounds. Fractional distillation and catalytic cracking are common methods used to process alkanes in refineries.

Alkanes play important roles in everyday life and industrial applications. They are used as starting materials for the synthesis of a wide range of fuels, lubricants and chemicals. For example, propane is a major component in liquefied petroleum gas (LPG), which is widely used in heating, cooking and automobile applications. Various higher alkanes are also used in making candles, waxes and lubricants due to their non-reactive nature.

Environmental impact of alkanes

While alkanes have important practical applications, their combustion can contribute to environmental issues. The burning of alkanes releases greenhouse gases such as carbon dioxide, which contribute to climate change. In addition, incomplete combustion of alkanes can produce carbon monoxide, a toxic compound harmful to both health and the environment.

Environmental awareness and regulatory measures aim to reduce the climate impact of alkanes by promoting clean combustion technologies and alternative energy sources. The introduction of catalytic converters in vehicles and emission limits on industrial processes are efforts to reduce the pollutant gases contributed by alkane combustion.

Conclusion

Alkanes are one of the simplest but fundamental groups of hydrocarbons, with unique properties and wide applications. Understanding their structure, behaviour in chemical reactions, and use in practical scenarios highlights their importance in both chemistry and various industrial sectors. Ensuring the sustainable use of alkanes while minimising environmental impacts remains an important focus of ongoing research and technological development.


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Hydrocarbons

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