Lewis Structure Generator
Hydrogen cyanide · HCN · Reviewed guide

HCN Lewis Structure

HCN is H–C≡N with one lone pair on nitrogen. Carbon and nitrogen are connected by a triple bond, and the molecule is linear.

Open HCN in the generatorSee drawing steps
HCN
H–C≡N:
One lone pair remains on nitrogen
Valence electrons10
ConnectivityH–C–N
GeometryLinear
Bond angle180°

How to draw HCN

  1. Count 10 electrons.
    H contributes 1, C contributes 4 and N contributes 5.
  2. Use H–C–N connectivity.
    Hydrogen cannot be central.
  3. Complete nitrogen's octet.
    A single-bond skeleton leaves carbon short of an octet.
  4. Form a C≡N triple bond.
    Two nitrogen lone pairs become additional bonding pairs.
  5. Leave one lone pair on nitrogen.
    All formal charges are zero.

Electron check

The H–C bond uses 2 electrons, the C≡N bond uses 6, and the nitrogen lone pair uses 2, for 10 total.

Geometry

Carbon has two electron domains, so H–C–N is linear. The lone pair is on terminal nitrogen and does not bend the carbon center.

Common mistakes

  • Putting hydrogen between carbon and nitrogen.
  • Drawing only a C=N double bond, which leaves carbon short of an octet.
  • Forgetting the nitrogen lone pair.
  • Calling HCN bent because nitrogen has a lone pair.

Reviewed July 16, 2026. Educational reference only.