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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Octahedral

Six domains pointing to the corners of an octahedron: four in a square plane and two above and below, with 90° between neighbours and 180° between opposite positions. It is the electron-domain geometry for SN = 6 and the shape of AX6\mathrm{AX_6}.

Central S atom bonded to 6 F atoms, with no lone pairs.FFFSFFF90°180°Ideal bond angles: 90°, 180°
SFX6\ce{SF6}: every F–S–F angle is 90° or 180°.

Example

PFX6X−\ce{PF6-} and SiFX6X2−\ce{SiF6^2-} are octahedral. One lone pair gives square pyramidal (BrFX5\ce{BrF5}); two, placed opposite, give square planar (XeFX4\ce{XeF4}).

See alsoSquare pyramidalSquare planarSteric number