Here's why:
* Electron Configuration: Gallium's electron configuration is [Ar] 3d10 4s2 4p1.
* Valence Electrons: Valence electrons are the electrons in the outermost energy level, which for gallium are the electrons in the 4s and 4p orbitals.
* Counting Valence Electrons: There are 2 electrons in the 4s orbital and 1 electron in the 4p orbital, giving a total of 3 valence electrons.
