Hydrogen Cyanide (HCN)

Linear triatomic with triple bond; highly toxic. Shows σ/π separation clearly. Teaching note: figures illustrate qualitative electronic structure; quantitative benchmarking should use larger bases, dispersion, and experimental structures.

Geometry

Linear

Polarity

Polar

Bond angle

180°

Hybridisation

sp (C and N)

VSEPR

AX2

Bonds

1 C–H σ + 1 C≡N (1σ + 2π) · 1 lone pair on N

Molecular orbitals

10 valence MOs; triple bond (1σ + 2π) between C and N plus C–H σ.

SMILES

C#N

Electron density: spin-paired GPAW (PBE) on an isolated gas-phase geometry; molecular orbitals: restricted mean-field RHF with sto-3g in PySCF unless noted.

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More molecules

• Dihydrogen (H2)
• Dinitrogen (N2)
• Dioxygen (O2)
• Difluorine (F2)
• Hydrogen fluoride (HF)
• Carbon monoxide (CO)
• Hydrogen chloride (HCl)
• Dichlorine (Cl2)
• Water (H2O)
• Hydrogen sulfide (H2S)
• Ammonia (NH3)
• Methane (CH4)
• Ethane (C2H6)
• Propane (C3H8)
• Ethene (C2H4)
• Ethyne (C2H2)
• Formaldehyde (CH2O)
• Methanol (CH3OH)
• Ethanol (C2H5OH)
• Acetic acid (CH3COOH)
• Benzene (C6H6)
• Pyridine (C5H5N)
• Carbon dioxide (CO2)
• Ozone (O3)
• Sulfur dioxide (SO2)
• Dinitrogen oxide (N2O)
• Phosphine (PH3)
• Silane (SiH4)
• Boron trifluoride (BF3)
• Chloromethane (CH3Cl)
• Methylamine (CH3NH2)
• Butane (C4H10)
• Sodium Chloride (NaCl)
• Nitric Oxide (NO)
• Nitrogen Dioxide (NO2)
• Carbon Tetrachloride (CCl4)
• Phosphorus Trichloride (PCl3)
• Sulfur Hexafluoride (SF6)
• Xenon Difluoride (XeF2)
• Vinyl Chloride (C2H3Cl)
• Formic Acid (HCOOH)
• Carbon Disulfide (CS2)
• Chlorine Trifluoride (ClF3)