Here's why:

* Group Number: Group 3A (also known as Group 13) refers to the elements in the third column of the periodic table.

* Valence Electrons: Valence electrons are the electrons in the outermost shell of an atom, which are involved in chemical bonding.

* Periodic Trends: The number of valence electrons generally corresponds to the group number for the main group elements (Groups 1-2 and 13-18).

Examples of Group 3A Elements:

* Boron (B)

* Aluminum (Al)

* Gallium (Ga)

* Indium (In)

* Thallium (Tl)

All of these elements have 3 valence electrons in their outermost shell.