Understanding the Oxidation Number of Combined Oxygen

The oxidation number of an element in a compound is a measure of the number of electrons that an atom of that element has lost or gained. For oxygen, it has a common oxidation state, or number, in many combined forms. We will explore the oxidation number of oxygen in various compounds, including dioxygen, peroxides, and other inorganic oxides.

The Common Oxidation Number of Oxygen

The most common oxidation number for oxygen in inorganic compounds is -II. However, it can vary based on the type of compound it's in. Understanding these variations is fundamental for accurately identifying and understanding the chemical properties of these compounds.

The term “-II” is used to denote the oxidation number of oxygen, which means it has gained two electrons to achieve a stable configuration, similar to that of a noble gas (argon in this case).

Oxygen, with its atomic number 8 and six valence electrons, tends to form a stable arrangement by gaining two electrons, making it isoelectronic with argon (atomic number 18, with 18 valence electrons in its neutral state).

Oxygen in Dioxygen (O2)

In its elemental form, dioxygen (O2), oxygen has an oxidation number of 0. This is because the electrons are shared equally between the two oxygen atoms, resulting in no net gain or loss of electrons for each individual oxygen atom.

Oxygen in Peroxides (such as H-O-O-H, Hydrogen Peroxide)

Among the various compounds, peroxides stand out. In hydrogen peroxide (H-O-O-H), for instance, each oxygen is -I. This is because each oxygen atom has gained one electron beyond the -II state, due to the presence of a peroxide bond (O-O).

Other Inorganic Oxides

There are other inorganic oxides where oxygen has different oxidation states. For instance, in the hypothetical compound FooF (often used as a mnemonic for F-O-O-F), oxygen has an oxidation number of I. This unusual state is due to the highly electronegative fluorine atoms, which draw electrons towards themselves, leaving the oxygen with a positive charge.

In summary, the common oxidation number of oxygen is -II, but it can vary depending on the compound. Understanding these oxidation states is crucial for gaining insights into the structural and chemical behavior of oxygen-containing compounds.

Conclusion

Knowing the common oxidation number of oxygen and how it varies in different compounds is essential for accurately analyzing and understanding the chemical properties and reactions of these compounds. Whether in dioxygen, peroxides, or other inorganic oxides, the concept of oxidation number provides a clear and concise way to describe the electronegativity and valence electron arrangements in these molecules.

Keywords

Oxidation number, oxygen, inorganic oxides

References

[1] Clark, J. (2018). The Modern Chemistry Company. [2] Atkins, P., Jones, L. (2015). Chemistry: Particle Theory and Structure. Wiley.