Hybridisation of carbon
A short walkthrough of how a carbon atom mixes its 2s and 2p orbitals into sp, sp² and sp³ hybrids, and how that fixes the bond angles and σ/π bonds you meet across organic chemistry.
What is hybridisation?
Mixing atomic orbitals on an atom to make a set of equal-energy hybrid orbitals. Carbon first promotes a 2s electron into the empty 2p (the excited state), giving four unpaired electrons to bond with.
Count the atoms on the carbon
If the carbon is bonded to:
• 4 atoms → sp³ (109.5°, tetrahedral)
• 3 atoms → sp² (120°, trigonal planar)
• 2 atoms → sp (180°, linear)
σ and π bonds
The first bond between two atoms is a σ bond (head-on overlap of hybrid orbitals). Any extra bonds are π bonds from side-on overlap of leftover p orbitals, so C=C is 1σ + 1π and C≡C is 1σ + 2π.
Get a mini lesson like this every week
Join the Mr Khemistry Telegram group for bite-sized lessons, exam tips and quick answers to the questions that trip students up.
Prefer a real class? Book a trial H2 Chemistry lesson.