Final answer:
The electron configuration of gallium (Ga) is [Ar]4s²3d±04p¹, based on its position on the periodic table. When gallium forms a Ga³+ ion, it loses three electrons, which leads to a [Ar]3d±0 configuration.
Step-by-step explanation:
The electron configuration of gallium (Ga) can be predicted based on its position on the periodic table. Gallium is element number 31, positioned just after the first row of transition metals. To write its electron configuration, you start with the noble gas preceding it, which is argon (Ar), and then add electrons following the order of the orbital levels.
Gallium's configuration is written as [Ar]4s²3d±04p¹. The notation explains that gallium has the core electron configuration of argon, followed by two electrons in the 4s orbital, ten electrons filling the 3d orbital, and finally one electron in the 4p orbital. This arrangement arises because orbitals fill according to increasing energy, with the 4s orbital filling before the 3d, despite being of a higher principal quantum number.
When gallium forms a Ga³+ ion, it loses the three electrons in the outermost orbitals, resulting in a stable configuration of [Ar]3d±0, which is often encountered in heavier p-block elements and is sometimes referred to as pseudo noble gas configurations.