mercurous oxide; mercury(I) oxide
Chemical compound with formula Hg₂O. Used in specialized chemical contexts.
Mercury(I) oxide is unstable and easily decomposes with light or heat.
mercuric oxide; mercury(II) oxide
Chemical compound with formula HgO. More stable than mercurous oxide; historically used in batteries and as a pigment.
Mercury(II) oxide decomposes into mercury and oxygen when heated.