Question

Why is boron oxide said to be amphoteric

Answer 1

Hence, it is said to be acidic. But, in the case of aluminium, since it is a metalloid( neither exactly a metal nor a non metal) and has decreased non metallic properties compared to boron, the oxide of aluminium is amphoteric( neither acidic nor basic) in nature.

hope it clarifies ur doubt dear friend...

Answer 2

While moving down the group, acidic strength decreases and basic strength increases.

The acidic character of oxides of group 13 decreases down the group, because non-metallic character of elements decreases down the group and metallic character increases.

And we know that oxides of metals are basic in nature and oxides of non-metals are acidic in nature. So acidic character of oxides of group 13 decreases down the group.

For example boron (1st element of group 13) is non-metal, so its oxide is acidic.

Aluminum (2nd element of group 13) shows characteristics of both metal and non-metal, so its oxide shows amphoteric nature.

As we go down the group, indium and thalium (4th and 5th element of group 13) show metallic properties, so their oxides are basic.

I hope this will help.