* M represents a metal element.

* O represents oxygen.

* The subscript 3 indicates that there are three oxygen atoms for every two metal atoms in the compound.

Examples of metallic oxides with the M2O3 formula include:

* Aluminum oxide (Al2O3): This is a common oxide found in bauxite ore and is used in various applications, including ceramics, abrasives, and aluminum production.

* Iron(III) oxide (Fe2O3): This is the primary component of rust and is also used as a pigment in paints.

* Chromium(III) oxide (Cr2O3): This oxide is used as a green pigment in paints and ceramics.

Properties of M2O3 compounds:

* Ionic bonding: M2O3 compounds are typically ionic, meaning they are formed by the electrostatic attraction between positively charged metal ions and negatively charged oxide ions.

* High melting and boiling points: Due to the strong ionic bonds, these compounds have high melting and boiling points.

* Insoluble in water: Most M2O3 compounds are insoluble in water.

* Basic oxides: M2O3 compounds are generally basic oxides, meaning they react with acids to form salts and water.

Note: The specific properties of a particular M2O3 compound will depend on the specific metal element involved.