* Sodium is in group 1 of the periodic table, meaning it has a +1 charge when it forms an ion (Na⁺).
* Oxygen is in group 16 of the periodic table, meaning it has a -2 charge when it forms an ion (O²⁻).
To form a neutral compound, you need two sodium ions (2 x +1 = +2) to balance out the charge of one oxygen ion (-2). This results in the formula Na₂O.
