Molecular Structures

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Molecular Structures

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Molecular geometry depicts the three-dimensional spatial arrangement of atoms, valence electrons, and bonds that create a molecule. The structure of a molecule contributes to its chemical and physical properties, such as magnetism, color, polarity, and reactivity. The VSEPR (valence shell electron pair repulsion) theory can be used to predict the shape of molecules based on the electrostatic repulsion between electron pairs within the molecule. The following table summarizes the notation, number of lone pairs of electrons, shape, bond angle(s), and structure of different molecular geometries predicted by VSEPR theory. Note that for molecules with lone electron pairs, the angles predicted by VSEPR theory are approximations. The actual angle differs from the ideal angle depending on the number of lone electron pairs on the central atom and their spatial arrangement. As a result, the lone pair–bond pair electron repulsions deviate the ideal bond angle to a lower value.

Using the radio buttons, choose between the various molecular configurations to see the corresponding shape in three dimensions. The image can be rotated by dragging it.

Notation	Lone Electron Pairs	Shape	Expected Bond Angles (Bond angle of example)	Example	View Structure
${AX}_{2}$	$0$	$Linear$	$180 °$	${CO}_{2}$
${AX}_{3}$	$0$	$Trigonal Planar$	$120 °$	${BF}_{3}$
${AX}_{2} E$	$1$	$Bent$	$120 ° (119 °)$	${SO}_{2}$
${AX}_{4}$	$0$	$Tetrahedral$	$109.5 °$	${CH}_{4}$
${AX}_{3} E$	$1$	$Trigonal Pyramidal$	$109.5 ° (107 °)$	${NH}_{3}$
${AX}_{2} E_{2}$	$2$	$Bent$	$109.5 ° (104.5 °)$	$H_{2} O$
${AX}_{5}$	$0$	$Trigonal Bipyramidal$	$90 °, 120 °, 180$	${PCl}_{5}$
${AX}_{3} E_{2}$	$2$	$T - Shaped$	$90 °, 120 °, 180 °$	${BrF}_{3}$
${AX}_{4} E$	$1$	$See - Saw$	$90 °, 120 °, 180 ° (173 °, 101.6 °)$	${SF}_{4}$
${AX}_{2} E_{3}$	$3$	$Linear$	$90 °, 120 °, 180 °$	${XeCl}_{2}$
${AX}_{6}$	$0$	$Octahedral$	$90 °, 180 °$	${SF}_{6}$
${AX}_{5} E_{}$	$1$	$Square Pyramidal$	$90 °, 180 ° (84.8 °)$	${BrF}_{5}$
${AX}_{4} E_{2}$	$2$	$Square Planar$	$90 °, 180 °$	${XeF}_{4}$