[libra78wolf]

2Mg+0₂-->2MgO
is the molecular equation,
would the net ionic equation be
2Mg²⁺+2O^2--->2MgO

[AWK]

Please, do not write an ionic equation for reaction of molecules
2Mg + O2 = MgO
MgO itself is a ionic compound (Mg2+O2-) but usually is written as molecule without charges shown

[jdurg]

The burning of Magnesium metal in oxygen has no 'net ionic equation'.  At no point in the reaction are the species in an ionic form.  As was said earlier, the product of the reaction is an ionic compound, but the reaction itself is not.  Therefore, there is no net ionic equation.  Even if this were an aqueous solution, there would be no net ionic equation because the O(2-) ion does not exist in an aqueous solution.  It immediately attacks a water molecule, or any other proton donator, to form OH-.