Question

Which chlorine atom is more electronegative in the following
A. \[C{H_3} - Cl\]
B. \[C{H_3} - C{H_2} - Cl\]
C. \[H - C Cl(C{H_3})_2\]
D. \[C{H_3} - C{H_2}C Cl(C{H_3})_2\]

Answer 1

Hint: Electronegativity is defined as the tendency of an atom to attract the shared pair of electrons towards itself. If a more electronegative group is attached to $Cl$ then it will withdraw electron density from $Cl$ towards itself. For example, Fluorine. If a less electronegative element is attached to $Cl$ then $Cl$ will withdraw electron density from it. For example, metals

Complete step-by-step answer:Electronegativity is a measure of an atom's ability to attract shared electrons toward itself and here in this problem chlorine, which is more electronegative than carbon is mentioned. Therefore with an increase in the number of the alkyl groups in the carbon center, the electron density increases gradually.
As we know $Cl$ tends to attract electrons from the attached bond with itself. From the four given options, we can see here the number of the alkyl group on the carbon center increases from compound A to D.
With increasing electron density on carbon chlorine attracts electron density towards itself, and as a result of electronegativity character also increases. In compound A, there is only one alkyl group, $-C{{H}_{3}}$ and in compound (B) only one $-{{C}_{2}}{{H}_{5}}$ group is attached with carbon atom. so, here chlorine atom is not the most electronegative.



But compound (D) contains three alkyl groups (two $-C{{H}_{3}}$ and one $-{{C}_{2}}{{H}_{5}}$ group) are attached with carbon atom, having (+I) effect, making it the most electronegative one than compound C (Containing two $-C{{H}_{3}}$ group).


Option ‘D ’ is correct

Note: An element say X has some value of electronegativity say A. Then ${X^ + }$ will have a greater value of electronegativity than A. This is because the element X will pull more electron density to neutralize its positive charge. Contrary, ${X^ - }$ will have less electronegativity value than A because of the electron electron repulsion between the negative charge and the shared pair of electrons that the element will attract.