VSEPR Theory
VSEPR Theory

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VSEPR Theory [Valence Shell Electron Pair Repulsion Theory] -Applications-

1) Molecules containing five electron pairs-

a)Molecules containing one lone pair and four bond pair(bp) of electrons [AB4L]-

Ex – SF4

In SF4 molecule four bond  pair and one lone pair (lp)  of electrons are present around the central Sulphur atom. lone pair is present in equatorial position . The distortion is due to the presence of lone pair .

lp-bp > bp-bp

Geometry becomes distorted  or like see saw. The bond angle in SF4 are 890 and 1170 instead of 900 and 1200 respectively.

VSEPR Theory

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b)Molecules containing two lone pair and three bond pair of electrons [AB3L2]-

Ex- ClF3

In ClF3  molecule three bond  pair and two lone pair  of electrons are present around the central Chlorine atom. Both lone pairs are  present in equatorial positions . The distortion is due to the presence of lone pairs .

lp – lp >  lp-bp > bp-bp

Geometry becomes ‘ T’ shaped . The bond angle in ClF3  is 87.60  instead of 900.

VSEPR Theory

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c)Molecules containing three lone pair and two bond pair of electrons [AB2L3]-

Ex – XeF2

In XeF2  molecule two bond  pair and three lone pair  of electrons are present around the central Xenon atom. Three lone pairs are  present in equatorial position . In this case net repulsion on the bonds due to lone pairs is zero .

lp – lp >  lp-bp > bp-bp

Geometry becomes  linear  . The bond angle is 1800.

VSEPR Theory

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2) Molecules containing Six electron pairs-

a)Molecules containing one lone pair and five bond pair of electrons [AB5L]-

Ex – BrF5

In BrF5 molecule 5 bp and 1 lone pair are present . Out of 6 electron pairs , one position is occupied by a lone pair . Since all the positions in octahedral geometry are equivalent .So lone pair may be placed at any position.

lp-bp > bp-bp

Geometry of BrF5 is square pyramidal.

VSEPR Theory

 

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b)Molecules containing two lone pair and four bond pair of electrons [AB4L2]-

Ex – XeF4

The six electron pairs has octahedral geometry but in XeF4 molecule 4 bp and 2 lone pairs are present.So two positions are occupied by 2 lone pairs .  Hence geometry becomes square planar.

VSEPR Theory

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