Question

Which has the highest nucleophilicity?
A. $F^ -$
B. $OH^ -$
C. $CH_3^ -$
D. $NH_2^- $

Answer 1

Hint : To determine the element with highest nucleophilicity, we need to know the difference between nucleophile and electrophile, and how the transfer of electrons determine whether an element is nucleophile or electrophile.

Complete Step by Step Answer:-
Nucleophilicity can be explained as : “giving away its elements”. A nucleophile is the one that donates an electron pair to an electrophile to form a chemical bond in relation to a reaction. Both nucleophile and electrophile are the opposite to each other, hence we can say less the electrophilicity more the nucleophilicity and vice versa.

A nucleophile is a substance or molecule that can donate electrons and are electron rich species. They are typical definitions of Lewis Bases and electrophile are electron deficient molecules.

In the above compounds,$ CH_3^ - $ has the lowest electrophilicity because in $CH_3^ - $ the extra electron is in ionic bond with the compound, whereas the compound will be in its octet state if the electron was not there. Hence in order to attain the octet state the compound will give away its extra electron and as we all know it's difficult to break a covalent bond as compared to ionic bond .Hence $CH_3^ - $ has the highest nucleophilicity and it's convenient for the compound to give away the extra electron .

So, the correct option is C. $CH_3^ - $

Note:-
While solving the question students generally get confused between electrophilicity and nucleophilicity. They also make mistakes in determining the nature of bond between compounds and how electrons are shared between them.