Answer: To find the ground-state electron configuration of O²⁻ (oxide ion), we first need to determine the atomic number of oxygen and then add two extra electrons to represent the ion's charge.
The atomic number of oxygen (O) is 8. Oxygen normally has 8 electrons in its neutral state, but since we have an oxide ion (O²⁻), it means it has gained two extra electrons.
The electron configuration of a neutral oxygen atom (O) is: 1s² 2s² 2p⁴
To represent the oxide ion (O²⁻) with two additional electrons, we add these electrons to the existing configuration:
1s² 2s² 2p⁶
The complete ground-state electron configuration of O²⁻ (oxide ion) is: 1s² 2s² 2p⁶