On the other hand the stability of the known oxygen compounds increases with the atomic weight, thus iodine pentoxide is, at ordinary temperatures, a well-defined crystalline solid, which is only decomposed on heating strongly, whilst chlorine monoxide, chlorine peroxide, and chlorine heptoxide are very unstable, even at ordinary temperatures, decomposing at the slightest shock.
Three oxides are known: chlorine monoxide, Cl 2 0, chlorine peroxide, C102, and chlorine heptoxide, C1207.
Chlorine heptoxide was obtained by A.
(See Iron And Steel.) Compounds Manganese forms several oxides, the most important of which are manganous oxide, MnO, trimanganese tetroxide, Mn304, manganese sesquioxide, Mn203, manganese dioxide, Mn02, manganese trioxide, Mn03, and manganese heptoxide, Mn207.
Manganese heptoxide, Mn 2 0 7, prepared by adding pure potassium permanganate to well cooled, concentrated sulphuric acid, when the oxide separates as a dark oil (H.