A formula mass of substance is a sum of the average atomics masses of each atom represented in the chemical formula and is expressed in atomic mass units.the formula mass of covalent compound is also called the molecular mass
Sodium has 11 protons and Magnesium has 12. The way that the periodic table is set up doesn't allow for any elements to be in between. The element would have to have 11.5 protons, which is impossible
