Question

VSEPR notation of \[PC{l_5}\] , \[{H_2}O\] and \[IC{l_4}^ - \] are:
A.\[PC{l_5} - A{X_5},\,{H_2}O - A{X_{2}}{E_2},\,IC{l_4}^ - - A{X_{4}}{E_2}\]
B.\[PC{l_5} - A{X_5},\,{H_2}O - A{X_{2}}{E_{}},\,IC{l_4}^ - - A{X_{4}}E\]
C.\[PC{l_5} - A{X_5},\,{H_2}O - A{X_{2}},\,IC{l_4}^ - - A{X_{4}}E\]
D.\[PC{l_5} - A{X_5},\,{H_2}O - A{X_{2}}{E_2},\,IC{l_4}^ - - A{X_{4}}E\]

Answer 1

Hint:To answer this question, you should recall the concept of VSEPR Theory. VSEPR stands for Valence Shell Electron Pair Repulsion and is used to predict the shape of the molecules from the electron pairs that surround the central atoms of the molecule.

Complete step by step answer:
According to VSEPR theory the number of Bond pairs = Total number of atoms linked to central atoms by single bonds and Number of lone pairs = Total number of electrons – No of shared pairs. Therefore we can say that:
$PC{l_5}$: has 5 bond pairs and 0 lone pairs $ - A{X_5}$
\[{H_2}O\]: has 2 bond pairs and 2 electron pairs−\[A{X_{2}}{E_2}\]
\[IC{l_4}^ - \]​: has 4 bond pairs and 2 electron pairs−\[A{X_{4}}{E_2}\] ​

Hence, we can conclude that the correct answer to this question is option A.

Additional information:
> Important characteristics of Bonding Molecular Orbitals.
> The probability of finding the electron in the internuclear region of the bonding molecular orbital is more than that of combining atomic orbitals.
> The presence of electrons present in the bonding molecular orbital is the cause of attraction between the two atoms.
> The bonding molecular orbital has lower energy as a result of attraction and hence has greater stability than that of the combining atomic orbitals.
> They are formed by the additive effect of the atomic orbitals so that the amplitude of the new wave is given by \[\Phi = \;{\Psi _A}\; + {\text{ }}{\Psi _B}\]
> They are represented by \[\sigma ,{\text{ }}\pi ,{\text{ and }}\delta \]
> Important characteristics of Anti-bonding Molecular Orbitals.
> The probability of finding the electron in the internuclear region decreases in the antibonding molecular orbitals. The electrons present in the antibonding molecular orbital result in the repulsion between the two atoms.
> The anti-bonding molecular orbitals have higher energy because of the repulsive forces and lower stability.
> They result from the subtractive effect of the atomic orbitals. The amplitude of the new wave is given by \[\Phi = \;{\Psi _A}\; - {\text{ }}{\Psi _B}\]
> They are represented by \[{\sigma ^ * },{\text{ }}{\pi ^ * },{\text{ }}{\delta ^ * }\]

Note: Major limitations of VSEPR theory include:
This theory fails to explain isoelectronic species as the chemical entity may vary in shapes despite having the same number of electrons.Cannot describe the compounds of transition metals as it does not take into account the associated sizes of the substituent groups and the lone pairs that are inactive.
An incorrect prediction that the halides of group 2 elements will have a linear structure, whereas their actual structure is a bent one.