Among the elements B, Al, C and Si,
1. which element has the highest first ionisation enthalpy?
2. which element has the most metallic character?
Justify your answer in each case.
|
Period |
Group-13 |
Group-14 |
|
2nd Period |
Boron |
Carbon |
|
3rd Period |
Aluminum |
Silicon |
(a) Ionisation enthalpy increases along a period (as we move from left to right in a period) with decrease in atomic size and decreases down the group with increase in atomic size. Hence, carbon has the highest first ionisation enthalpy.
(b) Metallic character decreases across a period but increases on moving down the group. Hence, aluminum has the most metallic character.
