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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Linear

A shape in which the central atom and the atoms bonded to it lie on a straight line, with a 180° bond angle. It arises from AX2\mathrm{AX_2} (SN = 2) and from AX2E3\mathrm{AX_2E_3}, where three lone pairs sit around the equator of a trigonal bipyramid.

Central C atom bonded to 2 O atoms, with no lone pairs.COO180°Ideal bond angle: 180°
COX2\ce{CO2}, AX2\mathrm{AX_2}: O=C=O at 180°.

Example

BeClX2\ce{BeCl2} and HCN\ce{HCN} are AX2\mathrm{AX_2}; IX3X−\ce{I3-} and XeFX2\ce{XeF2} are AX2E3\mathrm{AX_2E_3}. All four are linear.

See alsoSteric numberTrigonal bipyramidalBond angle