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पाठ्यक्रम

Carbon: A Versatile Element

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Topics

  • Definition: Tetravalency of Carbon
  • Definition: Catenation
  • Key Points: Carbon-A Versatile Element
Maharashtra State Board: Class 9

Introduction

Carbon was discovered by Antoine Lavoisier and is one of the most abundant elements on Earth. It exists in both free form and in combination with other elements. Unlike most elements, carbon can bond with itself and other elements to create simple molecules like methane and complex structures like DNA. All living structures are carbon-based.

  • Symbol of carbon: C
  • Atomic number: 6
  • Atomic mass: 12
  • Electron configuration: 2, 4
  • Valency: 4
  • Non-metallic element

Carbon is found in the earth's crust in the form of carbonate, coal, and petroleum, which contribute around 0.27%. Carbon dioxide is approximately 0.03% of the atmosphere's carbon. Some marine plants convert dissolved carbon into calcium carbonate, contributing to oceanic carbon storage.

Maharashtra State Board: Class 9

Occurrence of Carbon

The German chemist Wohler synthesised an organic compound (urea) from an inorganic compound (ammonium cyanate). Ever since then, many organic compounds have been made from inorganic compounds. Carbon was found to be the main element in all these compounds. Hence, organic chemistry is also referred to as the chemistry of carbon compounds.

\[\mathrm{NH}_4^+\mathrm{CNO}^-\xrightarrow{\mathrm{Heat}}\mathrm{NH}_2\mathrm{CONH}_2\]

Wohler 

The name ‘carbon’ is derived from the Latin word ‘carbo,’ meaning coal. It ranks 17th in terms of abundance in the earth's crust. Carbon is found in nature in free as well as compound states.

Free state: Found as diamond and graphite

Combined state:

  • As carbon dioxide and in the form of carbonates such as calcium carbonate, marble, and calamine (ZnCO₃)
  • Fossil fuels: coal, petroleum, natural gas
  • Carbonaceous nutrients: carbohydrates, proteins, fats
  • Natural fibres: cotton, wool, silk
Maharashtra State Board: Class 10

Characteristics of Carbon

1. Catenation Power

  • Carbon can form strong covalent bonds with other carbon atoms, creating long chains or ring structures.
  • Chains can be open (straight or branched) or closed (cyclic rings). This ability leads to the formation of millions of carbon compounds.

2. Molecular Mass Variation

Carbon compounds range from small molecules (e.g., methane, CH₄) to extremely large ones (e.g., DNA).

Examples of Carbon Compound Molecular Mass:

Carbon Compound Molecular Mass
Methane (CH₄) (The smallest carbon compound) 16
Cooking gas (C₃H₈ + C₄H₁₀) 44/58
Benzene (C₆H₆) 78
Camphor (C₁₀H₁₆O) 152
Penicillin (C₁₆H₁₈N₂O₄S) 334
Sugar (C₁₂H₂₂O₁₁) 342
Sodium dodecyl benzene sulfonate (a detergent) 347
Fat ~ 700
Starch ~ 10³
Cellulose ~ 10⁵
Protein ~ 10⁶
Polyethylene ~ 10⁶
D.N.A. ~ 10¹²

3. Bonding Capability (Tetravalency):

Carbon has four valence electrons and forms covalent bonds with up to four other atoms. It bonds with elements like hydrogen, chlorine, oxygen, nitrogen, sulphur, and phosphorus, creating a vast variety of compounds.

Example: Carbon and chlorine form different compounds based on the number of chlorine atoms attached: CH₄, CH₃Cl, CH₂Cl₂, CHCl₃, CCl₄.

4. Multiple Bond Formation:

Carbon atoms can form single, double, or triple covalent bonds, increasing the diversity of carbon compounds.

Examples:

  • Single bond: Ethane (CH₃-CH₃)
  • Double bond: Ethene (CH₂=CH₂)
  • Triple bond: Ethyne (CH≡CH)

5. Isomerism:

Carbon compounds exhibit isomerism, where molecules with the same molecular formula have different structures and properties. This further increases the number of possible carbon compounds.

CISCE: Class 10

Definition: Tetravalency of Carbon

The characteristic of the carbon atom, by virtue of which it forms four covalent bonds, is called the tetravalency of carbon.

CISCE: Class 10

Definition: Catenation

The property of self-linking of atoms of an element through covalent bonds in order to form straight chains, branched chains and cyclic chains of different sizes is known as catenation.

CBSE: Class 10
Maharashtra State Board: Class 10

Key Points: Carbon: A Versatile Element

  • Carbon forms many compounds, from simple ones like methane to complex ones like DNA, due to its bonding versatility.
  • Catenation allows carbon to form long chains or rings by bonding with itself.
  • Carbon forms single, double, and triple covalent bonds, leading to saturated and unsaturated compounds.
  • Being tetravalent, carbon forms four strong covalent bonds with elements like H, O, N, and Cl.
  • Isomerism increases the number of carbon compounds by allowing different structures with the same molecular formula.
 

Video Tutorials

We have provided more than 1 series of video tutorials for some topics to help you get a better understanding of the topic.

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Shaalaa.com | Carbon and Compounds part 21 (Examples)

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