The equation was not balanced correctly because it was balanced by changing a subscript instead of changing coefficients. The correctly balanced equation is 2Mg + O2= 2MgO.
Is this correct for you?
Answer:
There must be an additional Mg atom.
Explanation:
The valence of Mg is +2 which means it can give two electrons to any other element thereby forming chemical bond. For this, there is requirement of an element which has valence of -2 or an element which has a deficiency of 2 electron to reach stable state. Oxygen has a valency of -2 which means it can take two electrons from a donor element such as Mg.
In a balanced equation the number of electrons/atom/molecule/ion/radicals
on the right and left side of equation must be equal.
So the balanced equation between Mg and O will be -
[tex]Mg + O -----> MgO\\Or\\2 Mg + O_{2} ------> 2 MgO[/tex]
