Answer: -
Al₂O₃
Explanation: -
The atomic number of aluminium Al = 13
The electronic configuration of aluminium =2,8,3
To have 8 electrons in it's valence shell, it must lose 3 electrons.
So the valency of Al is +3.
The atomic number of oxygen is 8
The electronic configuration of O oxygen = 2,6
So to have 8 electrons in it's valence shell it must gain 2 electrons.
Thus the valency of O = -2.
The formula for aluminium oxide = Al ⁺³ O²⁻
= Al₂O₃