Question

which of the following are isoelectronic : CH3+ , H3O+ , NH3 and CH3- ?

Answer 1

CH3+ (linear) is the answer

Answer 2

Answer: The isoelectronic species are $H_3O^+,NH_3\text{ and }CH_3^-$

Explanation:

Isoelectronic molecules are defined as the molecules which have the same electronic structure and have the same number of valence electrons.

In the calculation, the positive charge is subtracted from the total number of valence electrons and negative charge is added to the total number of valence electrons.

Calculating the number of valence electrons for each molecule:

• For $CH_3^+$

Valence electrons of Carbon are 4 and that of Hydrogen is 1

Total number of valence electrons = $[4+(3\times 1)-1]=6$

• For $H_3O^+$

Valence electrons of Oxygen are 6 and that of Hydrogen is 1

Total number of valence electrons = $[6+(3\times 1)-1]=8$

• For $NH_3$

Valence electrons of Nitrogen are 5 and that of Hydrogen is 1

Total number of valence electrons = $[5+(3\times 1)]=8$

• For $CH_3^-$

Valence electrons of Carbon are 4 and that of Hydrogen is 1

Total number of valence electrons = $[4+(3\times 1)+1]=8$

As, the total number of valence electrons of $H_3O^+$, $H_3O^+$ and $CH_3^-$ are same. Thus, they are considered as isoelectronic species.