VSEPR Theory -applications part 3

VSEPR Theory

source : Slideplayer.com

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.

source : Wikipedia

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.

source : Chemistry Libre texts

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.

source : Quora.com

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.

source : en.wikipedia.org

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.