MCQ Detailed View

The methyl radical (•CH₃) is a fundamental species in organic chemistry and free radical reactions. It consists of a carbon atom bonded to three hydrogen atoms, with one unpaired electron remaining on the carbon atom. This makes the methyl radical highly reactive.

Electronic Structure:

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  Carbon has 4 valence electrons.

  
  


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  In the methyl radical, carbon shares 3 electrons with hydrogen atoms through covalent bonds.

  
  


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  This leaves 1 unpaired electron on carbon.

  
  


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  Hence, the total number of valence electrons around carbon is 7, not the complete octet (8).

  
  

Hybridization:

The carbon in a methyl radical undergoes sp² hybridization:

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  Three sp² hybrid orbitals overlap with the 1s orbitals of three hydrogens, forming three sigma (σ) bonds.

  
  


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  The unpaired electron resides in the remaining unhybridized p orbital.

  
  

Geometry:

The geometry of the methyl radical is trigonal planar (like carbocations) or very close to it. The bond angle is approximately 120°, which is consistent with sp² hybridization.

Importance:

Methyl radical plays a major role in free radical reactions, such as:

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  Halogenation of alkanes (chain propagation step).

  
  


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  Combustion reactions (intermediate species).

  
  


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  Polymerization (free radical chain reactions).

  
  

Why other options are incorrect:

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  Option 1 (sp³, 8 electrons): Incorrect, because methyl radical does not have a complete octet.

  
  


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  Option 2 (sp², 6 electrons): Wrong, since carbon has 7 electrons here, not 6.

  
  


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  Option 4 (sp, linear geometry): Incorrect, methyl radical is not linear; it is planar.

  
  

Key Point:

Methyl radical is sp² hybridized, contains 7 valence electrons, and has one unpaired electron in a p orbital, making it a reactive intermediate in many organic reactions.