Hybridization Types — Chemistry Mnemonic
Target: mnemonic for hybridization sp sp2 sp3 chemistry
Why is this hard to memorize?
Hybridization explains why molecules have the shapes they do — it's the orbital-level reason behind VSEPR predictions. For NEET and JEE, you need to map hybridization to geometry instantly: sp = linear (180°), sp² = trigonal planar (120°), sp³ = tetrahedral (109.5°), sp³d = trigonal bipyramidal, sp³d² = octahedral. You also need to identify hybridization from structure: count σ bonds + lone pairs on the central atom = steric number = hybridization. This topic is foundational for organic chemistry (sp³ carbon in alkanes, sp² in alkenes, sp in alkynes) and inorganic (XeF₂ = sp³d, XeF₄ = sp³d²).
Classic mnemonics you should know
"Steric Number: 2=sp, 3=sp², 4=sp³, 5=sp³d, 6=sp³d²"
Steric number = σ bonds + lone pairs on central atom. SN=2 → sp (BeCl₂), SN=3 → sp² (BF₃), SN=4 → sp³ (CH₄), SN=5 → sp³d (PCl₅), SN=6 → sp³d² (SF₆). Just count and look up.
"Single bond C = sp³(4 groups). Double bond C = sp²(3 groups). Triple bond C = sp(2 groups)."
For carbon in organic molecules: count the number of groups (atoms + lone pairs) around it. 4 groups = sp³, 3 = sp², 2 = sp. Each double/triple bond still counts as one group.
"sp-Line, sp²-Triangle, sp³-Tetra, sp³d-TBP, sp³d²-Octa — "L T T T O""
Same sequence as VSEPR but labeled by hybridization instead of electron pair count. The shapes are identical — hybridization is just the orbital explanation.
The complete list
- sp — Linear (180°)
- sp² — Trigonal planar (120°)
- sp³ — Tetrahedral (109.5°)
- sp³d — Trigonal bipyramidal
- sp³d² — Octahedral
- sp³d³ — Pentagonal bipyramidal
Frequently asked questions
How do I find hybridization quickly in an exam?
Count the steric number: number of atoms bonded to the central atom + number of lone pairs on it. SN=2 → sp, SN=3 → sp², SN=4 → sp³, SN=5 → sp³d, SN=6 → sp³d². For organic molecules, just count groups around the atom (double/triple bonds count as one group).
Why is BF₃ sp² but NF₃ sp³?
BF₃ has 3 bonding pairs and 0 lone pairs on B (SN=3 → sp²). NF₃ has 3 bonding pairs and 1 lone pair on N (SN=4 → sp³). The lone pair on nitrogen requires an extra hybrid orbital, changing the hybridization from sp² to sp³.
What is the hybridization of carbon in ethene and ethyne?
In ethene (C₂H₄), each carbon has 3 groups (2H + 1C with double bond) → sp². In ethyne (C₂H₂), each carbon has 2 groups (1H + 1C with triple bond) → sp. The remaining unhybridized p-orbitals form the π bonds.
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