There seems to be a misunderstanding in the question. There is no compound called "Carbonate Mg2". Here's why:

* Carbonate Ion: The carbonate ion is CO₃²⁻. It has a -2 charge.

* Magnesium Ion: Magnesium (Mg) forms a +2 cation (Mg²⁺).

To form a neutral compound, the charges must balance. Therefore, the correct formula for magnesium carbonate is MgCO₃.

Let me know if you have any other questions about chemical formulas!