Chemistry · Bonding and molecular shape

Molecular Geometry (VSEPR) Explorer

Set the number of electron domains around a central atom, then choose how many of them are lone pairs. The rest are bonded atoms. The model rotates the molecule and names the electron-domain geometry, the molecular shape, the bond angles, and the hybridization.

Valence shell electron pair repulsion (VSEPR) theory says that regions of electron density around a central atom spread as far apart as possible. Lone pairs take more room than bonding pairs, so they squeeze the bond angles.

Model notes

Notation: A is the central atom, X is a bonded atom, E is a lone pair. AXₘEₙ means m bonded atoms and n lone pairs. Electron domains = m + n. Only the 13 shapes that occur for a central atom with 2 to 6 electron domains are offered, so the lone pair slider has a different top value for each domain count.
The 3D picture is drawn at the ideal angles of the electron-domain geometry so that the arrangement stays clear. The real, measured angle of the example molecule is shown in the tiles and the table. Lone pairs squeeze the real angles below the ideal ones.
Example molecules and angles are textbook values: SO₂ 119°, NH₃ 107°, H₂O 104.5°, SF₄ 101.6° (equatorial) and 173° (axial), ClF₃ about 87.5°, BrF₅ about 85°. Values quoted for real molecules vary a little between sources and phases.
Polarity is stated for a molecule whose outer atoms are all the same. Different outer atoms, or bonds of unequal polarity, can change the answer. A molecule is nonpolar when its bond dipoles cancel by symmetry.
Hybridization is given by the number of electron domains: 2 sp, 3 sp², 4 sp³, 5 sp³d, 6 sp³d². This is a bonding model, and for heavier central atoms the use of d orbitals is debated.

Sources

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