Question:

The correct order of bond enthalpy \(\left( kJ mol ^{-1}\right)\) is :

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Remember that bond enthalpy generally decreases down a group due to the increase in atomic size and bond length.

Updated On: Jan 10, 2025
  • \(C - C > Si - Si > Ge - Ge > Sn - Sn\)

  • \(C - C > Si - Si > Sn - Sn > Ge - Ge\)

  • \(Si - Si > C - C > Ge - Ge > Sn - Sn\)

  • \(Si - Si > C - C > Sn - Sn > Ge - Ge\)

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The Correct Option is A

Solution and Explanation

Step 1: Consider the Trend Down the Group
Bond enthalpy generally decreases down a group in the periodic table. This is because as the atomic size increases, the bond length increases, and longer bonds are weaker.
Step 2: Analyze the Given Elements
The elements in question are C, Si, Ge, and Sn. They all belong to Group 14. Their atomic size increases down the group in the order:
\[\text{C} < \text{Si} < \text{Ge} < \text{Sn}.\]
Step 3: Determine the Bond Enthalpy Order
Since bond enthalpy decreases with increasing atomic size, the correct order of bond enthalpy is:
\[\text{C–C} > \text{Si–Si} > \text{Ge–Ge} > \text{Sn–Sn}.\]

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Concepts Used:

Chemical Bonding and Molecular Structure

Such a group of atoms is called a molecule. Obviously, there must be some force that holds these constituent atoms together in the molecules. The attractive force which holds various constituents (atoms, ions, etc.) together in different chemical species is called a chemical bond.

Types of Chemical Bonds:

There are 4 types of chemical bonds which are formed by atoms or molecules to yield compounds. 

  • Ionic Bonds - Ionic bonding is a type of chemical bonding which involves a transfer of electrons from one atom or molecule to another.
  • Covalent Bonds - Compounds that contain carbon commonly exhibit this type of chemical bonding. 
  • Hydrogen Bonds -  It is a type of polar covalent bonding between oxygen and hydrogen wherein the hydrogen develops a partial positive charge
  • Polar Bonds - In Polar Covalent chemical bonding, electrons are shared unequally since the more electronegative atom pulls the electron pair closer to itself and away from the less electronegative atom.

Factors Affecting Bond Enthalpy in Chemical Bonding:

  • Size of the Atom
  • Multiplicity of Bonds
  • Number of Lone Pair of Electrons Present
  • Bond Angle