Question

Which element has the most metallic character:
A. Boron
B. Aluminium
C. Indium
D. Thallium

Answer 1

Hint: We know that the metallic character shows a gradual increase on moving down a group in a periodic table and in the direction from left to right across a period; the metallic character decreases.

 Complete step by step answer:
We know that, in a periodic table on moving down a group, the metallic character shows a gradual increase. This is due to the fact that the atomic radius increases because of which electrons can be lost more quickly. Down the group, when atomic radius increases the attraction that exists between the nucleus and electrons of the outermost shell becomes less, due to an increased distance between them. As a result, the metallic character increases. Therefore, in the boron family, thallium is most metallic in nature.
On moving in the direction from left to right across a period, the metallic character shows a gradual decrease. This is due to the fact that the atomic radius decreases and atoms accept electrons more quickly. The attraction that exists between the nucleus and electrons of the outermost shell becomes strong, due to a decreased distance between them. As a result, the metallic character reduces.
Hence, we can say that thallium has the most metallic character.

So, the correct answer is “Option B”.

Note:
As we know that, in a periodic table, the metallic character shows a gradual increase down a group and reduces across a period. Boron belongs to the $13$ group of a periodic table. Aluminium, indium and thallium are the members of the boron family. Thallium is the biggest in size among all so we can conclude that it has the highest metallic character.