On the basis of VSEPR theory, prefict the shapes of the following molecules ions :
`(i)ClF_(3)" "(ii)BrF_(5)" "(iii)IF_(7)" "(iv)H_(3)O^(+)ion.`

Explanation

(i) Shape of `CIF_(3)` molecule. No of valence electrons on central Cl atom = 7
No. of F atoms linked by single covalent bonds =3
Total no. of electron pairs aroung Cl atom `=(7+3)/2=5`
Total no. of shared pairs =3
Number of lone pairs =5-3=2
The shape of the molecules is T-shaped.
(ii) Shape of `BrF_(5)` molecule. No of valence electrons on central Br atom = 7
No. of F atoms linked by single covalent bonds = 5
Total no. of electron pairs around central Br atom `=(7+5)/2=6`
No. of shared pairs = 5
No. of lone pairs =6-5=1
The shape of the molecule is square pyramidal.
(iii) Shape of `IF_(7)` molecule. No. of valence electrons on central I atom = 7
No of F atoms linked by single convalent bonds = 7
Total no. of electron pairs around central I atom `=(7+7)/2=7`
No. of shared pairs = 7
No. of lone pairs = 7 -7=zero
Shape of `IF_(7)` molecule is pentagonal bipyramidal.
(iv) Shape of `H_(3)O^(+)` ion. No of electrons on central O atom =6-1=5
No of H atoms linked by single covalent bonds =3
Total no. of electron pairs around central O atom `=(5+3)/2=4`
No, of shared pairs =3
No. of lone pairs =4-3=1
Shape of `H_(3)O^(+)` ion is pyramidal.