The non-metallic oxides They are binary-type compounds, which are formed from the combination of a non-metal and oxygen, the latter in particular in its oxidation number -2. For instance: Telluric anhydride, Carbon dioxide, Sulfuric anhydride.
It is usual that they are also recognized under the name of acid oxides or anhydrides, and that they are formulated using the symbol of the non-metallic element together with the valence of oxygen (2) plus oxygen together with the valence of the non-metallic element. In mathematical simplification it is common for the formulation to lose that shape. On the other hand, the bond between oxygen and the nonmetal is covalent.
Although non-metallic oxides can appear in all three states of aggregation, they are more frequently found in the gaseous form because their molecules tend to be quite small and not very polar. In this sense, it can be said that oxides of this type often have a rather low boiling and melting point.
About the physical properties These non-metallic oxides can be said to have various colors and lack metallic luster. Solids tend to be more brittle, some are harder and others are softer. They are not good conductors of heat and electricity. On the other hand, they tend to form oxoanion salts when they react with basic oxides.
Non-metallic oxides are often a root cause of environmental problems, since its presence in nature is a source of the diffusion of the greenhouse effect and acid rain.
Like almost everything about the combinations of atoms to form chemical compounds, there are three ways of naming them:
- Traditional nomenclature. According to the amount of oxidation states of the non-metallic element, the prefix and suffix that will complete the name of the non-metal that comes from the word anhydride is defined.
- When the nonmetal has only one oxidation state is named: anhydride / nonmetal name. For instance: silicon oxide (SiO2).
- When the nonmetal has two oxidation states is named: anhydride / nonmetal name (with suffix “bear” for the lowest oxidation state and “ico” for the highest oxidation state). For instance: phosphorous anhydride (P2OR3) and phosphoric anhydride (P2OR5).
- When the nonmetal has three oxidation states it is named: anhydride / nonmetal name (with prefix “hypo” and suffix “bear” for the lowest oxidation state, with suffix “bear” for the next oxidation state, and with suffix “ico” for the highest oxidation state. oxidation). For instance: hyposelenious anhydride (TeO), selenium anhydride (TeO2) and selenic anhydride (SeO3).
- When the nonmetal has four oxidation states is named: anhydride / nonmetal name (with prefix “hypo” and suffix “bear” for the lowest oxidation state, with suffix “bear” for the next oxidation state, with suffix “ico” for the next oxidation state , and with prefix “per” and suffix “ico” for the highest oxidation state). For instance: hypochlorous anhydride (Cl2O), chlorous anhydride (Cl2OR3), chloric anhydride (Cl2OR5) and perchloric anhydride (Cl2OR7).
- Stock nomenclature. It is written ‘oxide of’ and is completed with the non-metallic element followed by the oxidation number with which it acts (in Roman numerals) in parentheses. For instance: phosphorus (III) oxide (P2OR3).
- Systematic nomenclature. According to the number of atoms of the non-metallic element and oxygen, a prefix is formed for each element (‘mono’, ‘di’, ‘tri’, ‘tetra’, ‘penta’, ‘hexa’ or ‘hepta’) preceding ‘oxide of’ and ‘name of non-metallic element’. For instance: Dichloro heptaoxide (Cl2OR7).
Examples of non-metallic oxides
The following list will include twenty non-metallic oxides, under the traditional nomenclature:
| Telluric anhydride (TeO2) | Silicic anhydride (SiO2) |
| Nitrous anhydride (N2OR3) | Carbonaceous anhydride (CO) |
| Nitric anhydride (N2OR5) | Carbon dioxide (CO2) |
| Manganous anhydride (MnO2) | Hypochlorous anhydride (Cl2OR) |
| Manganic anhydride (MnO3) | Chlorous anhydride (Cl2OR3) |
| Permanganic anhydride (Mn2OR7) | Chloric anhydride (Cl2OR5) |
| Hypoiodine anhydride (I2OR) | Perchloric anhydride (Cl2OR7) |
| Iodine anhydride (I2OR3) | Hyposulfurous anhydride (SO) |
| Iodium anhydride (I2OR5) | Sulfur dioxide (SO2) |
| Periodic anhydride (I2OR7) | Sulfuric anhydride (SO3) |