Question

How does metallic character vary across the period? Explain.

Answer 1

Metallic character is directly proportional to the tendency of metal atoms to lose electrons.

Complete step by step answer:
When we go from left to right of the periodic table, i.e., across the period, the metallic character of the corresponding metal atom decreases. This can be explained as follows-
On moving from left to right across the periodic table, electrons get added to the same shell. Due this additional increase in the no. of electrons, the nucleus attracts the electrons more strongly. Hence, a greater force of attraction, i.e., effective nuclear charge is felt by the nucleus. This ultimately results in a decrease in the size of the atom. Consequently, the energy required to remove the outermost electron is too high and hence, the atom is not able to lose the electron more readily.
Since, the metallic character is defined by the ability of the atom to lose its outermost electron, it becomes less metallic as we go from left to right in the periodic table.

Additional information: The complete opposite situation takes place when we go down the group in the periodic table. As we go down the group, there is an increase in the no. of shell and each electron now gets added in the new shell. Now, as the distance of the outermost electron from the nucleus increases, there is a decrease in the effective nuclear charge felt by the outermost electron and hence it becomes comparatively easy for the metal atom to lose the electron. This results in an increase of metallic character down the group.

Note:
One must keep in mind that ionization energy and metallic character are inversely related. An increase in metallic character implies that less energy is required for loss of electron which gives low ionization energy and vice versa.