In group 13, the only metalloid, boron, is at the very top of the group. Explain why the rest of the group has metallic behavior

All group 13 elements have three valence electrons, which makes it somewhat easier for them to lose these 3 electrons than to gain 5 to complete their outer shell. Nonetheless, elements with fewer electron shells can gain electrons more easily. Since boron possesses only two electron shells, it has a similar likelihood of gaining and losing electrons, thereby acting as a metalloid. The other group members, equipped with additional electron shells, find it significantly simpler to shed their valence electrons, resulting in metallic behavior.