The chemical formula of benzene is C6H6, so it has six carbon (C) atoms and six hydrogen (H) atoms. Its chemical structure can be described as a hexagon ring with alternating double bonds, as shown in this illustration. The chemical structure of benzene shows that for each carbon atom, there is one hydrogen atom.
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