CIE AS Chemistry (9701) exams from 2022

Revision Notes

3.1.9 Planarity of Organic Molecules

Planar Molecules

  • Planar molecules have all their atoms in the same plane
    • Eg. linear, bent, trigonal planar and square planar

 

An Introduction to AS Level Organic Chemistry Planar Molecules, downloadable AS & A Level Chemistry revision notes

Molecules which have all their atoms in the same plane

  • The presence of an sp2 hybridised carbon can force the molecule to adopt a plane configuration (trigonal planar)
  • The 3 σ bonds position themselves in a trigonal planar position so that the bonding pair of electrons are as far away from each other and therefore minimise the repulsion between them
  • Eg. ethene

 

An Introduction to AS Level Organic Chemistry Planar Ethene, downloadable AS & A Level Chemistry revision notes

Ethene is a planar molecule with two trigonal planar centres around the carbon atoms

  • Eg. propene

 

An Introduction to AS Level Organic Chemistry Planar Propene, downloadable AS & A Level Chemistry revision notes

Propene has two trigonal planar centres around the carbon-carbon double bond and one tetrahedral centre

  • The presence of a sphybridised carbon can also force the molecule to adopt a planar configuration (linear)
  • The 2 σ bonds position themselves in a linear position to minimise the repulsion between the bonding pairs of electrons
  • ethyne

 

An Introduction to AS Level Organic Chemistry Planar Ethyne, downloadable AS & A Level Chemistry revision notes

Ethyne is a planar molecule with one planar centre: the molecule is linear

  • Eg. propyne

 

An Introduction to AS Level Organic Chemistry Planar Propyne, downloadable AS & A Level Chemistry revision notes

Propyne has one planar centre around the carbon-carbon triple bond (linear) and one tetrahedral centre

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