Which is the least electronegative element? A ) Lithium B ) Carbon C ) Boron D ) Fluorine
Hint: Consider the trends in electropositive and electronegative character, on moving from left to right in the second period of the periodic table.
Complete answer: > The elements lithium, carbon, boron and fluorine belong to the second period of the periodic table. In the second period of the periodic table, the elements present are lithium, beryllium, boron,carbon, nitrogen, oxygen, fluorine and neon. > In the periodic table, on moving from left to right, with increase in the periodic table, the electropositive character decreases and the electronegative character increases. On the left hand side of the periodic table, highly electropositive metals, such as lithium are present. On the right hand side of the periodic table, highly electronegative elements, such as fluorine are present. > Hence, in the second period of the periodic table, the least electronegative element is lithium. In fact, lithium is the most electropositive element in the second period of the periodic table.
Hence, the option A ) lithium is the correct answer.
Additional Information Option B ) carbon, option C ) boron and option D ) fluorine are incorrect answers because these elements are towards the right of lithium in the second period of the periodic table. Hence, these elements carbon, boron and fluorine) are more electronegative (less electropositive) than lithium.
Note: In any given period, alkali metals are least electronegative (most electropositive) metals and halogens are most electronegative (least electronegative) non metals.