Summary of Molecular Geometry and Hybridization

total # of
independent
electron pairs # of independent
bonding
electron pairs # of nonbonding
electron pairs Orbital geometry Molecular geometry Distortion? Hybridization Bond angles Examples

2 2 0 linear linear never sp 180^o CO₂, BeCl₂

3 3 0 trigonal planar trigonal planar possible* sp² 120^o BF₃, NO₃^-

3 2 1 trigonal planar bent always sp² 120^o NO₂^-

4 4 0 tetrahedral tetrahedral possible* sp³ 109.5^o CH₄, SO₄^2-

4 3 1 tetrahedral trigonal
pyramidal always sp³ 109.5^o NH₃, SO₃^2-

4 2 2 tetrahedral bent always sp³ 109.5^o H₂O, NH₂^-

5 5 0 trigonal
bipyramidal trigonal
bipyramidal possible* sp³d 90^o and 120^o PF₅

5 4 1 trigonal
bipyramidal distorted square
pyramidal
(see-saw) always sp³d 90^o and 120^o SF₄

5 3 2 trigonal
bipyramidal T-shaped always sp³d 90^o IF₃

5 2 3 trigonal
bipyramidal linear never sp³d 180^o I₃^-

6 6 0 octahedral
(square
bipyramidal) octahedral possible* sp³d² 90^o SF₆

6 5 1 octahedral
(square
bipyramidal) square
pyramidal always sp³d² 90^o IF₅

6 4 2 octahedral
(square
bipyramidal) square planar possible** sp³d² 90^o XeF₄

* Note: under distortion, "possible" means that the bond angles will be distorted when the outer atoms are not identical. For example, tetrahedral CH₄ (all outer atoms are H) has no distortion (all bond angles are exactly 109.5^o), but in tetrahedral CH₃F (three H and one F) the bond angles are slightly distorted from 109.5^o.

** For square planar molecules, distortion will occur if the outer four atoms are not symmetrically distributed: this needs to be considered on a case-by-case basis. (This geometry is very rare outside of transition-metal complexes, which we do not cover in Chem 101A.)

Note on molecular polarity: the following types of molecules are nonpolar: linear AB₂, trigonal planar AB₃, tetrahedral AB₄, trigonal bipyramidal AB₅, octahedral AB₆, square planar AB₄, and symmetric square planar AB₂C₂. Any other molecule having a single "central atom" will be polar, as long as the electronegativities of the elements that make it up are not equal. This includes molecules that have the above geometries but which have dissimilar outer atoms (such as tetrahedral CH₃F and linear O=C=S).

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total # of independent electron pairs	# of independent bonding electron pairs	# of nonbonding electron pairs	Orbital geometry	Molecular geometry	Distortion?	Hybridization	Bond angles	Examples
2	2	0	linear	linear	never	sp	180^o	CO₂, BeCl₂
3	3	0	trigonal planar	trigonal planar	possible*	sp²	120^o	BF₃, NO₃^-
3	2	1	trigonal planar	bent	always	sp²	120^o	NO₂^-
4	4	0	tetrahedral	tetrahedral	possible*	sp³	109.5^o	CH₄, SO₄^2-
4	3	1	tetrahedral	trigonal pyramidal	always	sp³	109.5^o	NH₃, SO₃^2-
4	2	2	tetrahedral	bent	always	sp³	109.5^o	H₂O, NH₂^-
5	5	0	trigonal bipyramidal	trigonal bipyramidal	possible*	sp³d	90^o and 120^o	PF₅
5	4	1	trigonal bipyramidal	distorted square pyramidal (see-saw)	always	sp³d	90^o and 120^o	SF₄
5	3	2	trigonal bipyramidal	T-shaped	always	sp³d	90^o	IF₃
5	2	3	trigonal bipyramidal	linear	never	sp³d	180^o	I₃^-
6	6	0	octahedral (square bipyramidal)	octahedral	possible*	sp³d²	90^o	SF₆
6	5	1	octahedral (square bipyramidal)	square pyramidal	always	sp³d²	90^o	IF₅
6	4	2	octahedral (square bipyramidal)	square planar	possible**	sp³d²	90^o	XeF₄