Question

Which of the following is most electronegative?
A. Carbon
B. Silicon
C. Lead
D. Tin

Answer 1

Hint: Electronegativity is defined as a measure of the tendency of an atom to attract a bonding pair of electrons. Down a group electronegative property decreases while across a period electronegativity value increases. We need to arrange the given elements according to their periods and groups.

Complete Solution :
On the periodic table, electronegativity generally increases as we move from left to right across a period and decreases as we move down a group. Hence, the most electronegative elements are found on the top right of the periodic table, while the least electronegative elements are found on the bottom left.
- Two main factors that affect the magnitude of electronegativity are – atomic size and nuclear charge. The smaller the size of an atom, the greater is the attraction for bonding electrons. Thus, atoms with small size are more electronegative. Electronegativity values increase with increase in nuclear charge.
- The elements, carbon, silicon, lead, and tin, all belong to group 14 (IV A). The atomic size increases down a group. Down a group, nuclear charge increases, but with the addition of new shells, the screening effect also increases. Thus, the attraction of the nucleus for the outermost electron goes on decreasing. Hence, down a group, atomic size is the deciding factor.
- Now, based on atomic size, carbon is smallest, then comes silicon, then tin and finally lead. Hence, due to increasing atomic size, carbon is the most electronegative among the given elements.
So, the correct answer is “Option A”.

Additional information: Fluorine which is the most electronegative element is assigned a value of 4.0, and values range down to caesium and francium which are the least electronegative elements at 0.7.

Note: The Pauling scale is the most commonly used to measure the electronegativity. Carbon has an electronegativity of 2.55, followed by Tin at 1.96, Silicon at 1.90 and the least electronegative would be Lead at 1.87.