Ionization energies
The first ionization energies of group 13 elements are less than the corresponding members of the alkaline earths.
The sharp decrease in I. E. from B to Al is due to increase in size. In case of Ga, there are ten d-electrons in its inner electronic configuration.
The very high value of 3 rd I. E. of thallium indicates that + 3 O. N. state is not stable, rather + 1 is more stable for thallium.
Electropositive( or metallic) character
the elements of group 13 are less electropositive as compared to elements of group 2. On moving down the group the electropositive( metallic) character increases because ionization energy decreases. For e. g., Boron is a non-metal white the other elements are typical metals.
Oxidation states
The common oxidation states of group 13 elements are + 3 and + l. The stability of the + 1 oxidation state increases in the sequence Al < Ga < In < Tl, Due to Inert pair effect.
Element |
B |
Al |
Ga |
In |
Tl |
Oxidation state |
+ 3 |
+ 3 |
+ 3, + 1 |
+ 3, + 1 |
+ 3, + 1 |
Chemical reactivity of Gr. 13 Elements All elements in their compounds exhibit the oxidation state of + 3 and + 1. Hydrides
• None of the group 13 elements reacts directly with hydrogen. However, a no. of hydrides of these elements have been prepared by indirect methods. The boron hydrides are called boranes & classified in two series:
( a) |
BnHn + 4 called nidoboranes |
( b) |
BnHn + 6 called arachnoboranes |