Nonmetal oxides

Let us know about nonmetal oxides. Nonmetallic oxides They are also called acid oxides, because they react with water to form acids or bases to form salts. This can be seen in the case of compounds such as sulfur dioxide (SO 2 ) and chlorine oxide (I), which react with water to produce the weak acid H 2 SW 3 and HOCl, respectively.

Nonmetal oxides are covalent, in contrast to metallic ones which represent oxides of ionic character. Oxygen has the ability to form bonds with heavier elements due to its electronegativity, making it an excellent base for a variety of chemical compounds.

Among these compounds is the possibility that the oxygen diion binds to a metal or a nonmetal to form oxygen. Oxides are chemical compounds common in nature, in which at least one oxygen atom is attached to another element, metal or metal.

This element is presented in a state of solid, liquid or gaseous aggregation, depending on the element to which oxygen is bound and the oxidation number. Between one oxide and another, even when oxygen is bound to the same element, its properties can differ greatly; For this they must be fully recognized to avoid confusion.

How are they made?

As explained above, acid oxides are formed after the bonding of a non-metallic cation with an oxygen metallization (O 2- ).

This type of compound is found in elements located on the right side of the periodic table (metallic substances usually produce amphoteric oxides), and in transition metals in higher oxidation states.

A very common way to form a nonmetal oxide is through the decomposition of ternary compounds called oxidizers, which are formed by a nonmetal oxide and water.

It is for this reason that nonmetal oxides are also called anhydrides, since they are compounds that are characterized by the loss of a water molecule during their formation.

In the decomposition reaction of sulfuric acid at high temperature (400 °C), for example, H 2 SW 4 it completely decomposes to the point of becoming SO vapor 3 and H 2 or, according to the reaction: H 2 SW 4 + heat → SO 3 + H 2 O

Another way to form non-metallic oxides is through direct oxidation of the elements, as in the case of sulfur dioxide: S + O 2 → Sub 2.

It also occurs in the oxidation of carbon with nitric acid to form carbon dioxide: C + 4 HNO 3 → CO 2 + 4NO 2 + 2H 2 O.


In order to name a nonmetal oxides, several factors must be taken into account, such as the oxidation number that the non-metallic type of element can have and its stoichiometric characteristics.

Its nomenclature is the same as that of the parent oxide. Furthermore, depending on the element with which oxygen combines to form an oxide, oxygen or a non-metallic element will be written first in its molecular formula; However, this does not affect the naming rules for these compounds.

Systematic Nomenclature with Roman Numerals

The element on the right is named first in the formula to name this type of oxide using the old stock nomenclature (arranged with Roman numerals).

If it is a non-metallic element, the suffix “euro” is added, then the preposition “d” and it ends by naming the element on the left; If it is oxygen, it begins with “oxide” and is the name of the element.

The oxidation state of each atom is finalized by placing its name, without spaces, in Roman numerals and between parentheses; In the case of having only one valence number, it is omitted. Applies only to elements that have a positive oxidation number.

systematic naming with prefixes

When using systematic nomenclature with prefixes, the same principle is used in stock nomenclature, but Roman numerals to indicate oxidation states are not retained.

Instead, the number of atoms in each should be indicated by the prefixes “mono”, “di”, “tri”, and so on; It should be noted that if there is no possibility to confuse a monoxide with another oxide, this prefix is ​​omitted. For example, for oxygen, “mono” is omitted in SeO (selenium oxide).

traditional nomenclature

When conventional nomenclature is used, the generic name is put first – in this case the word”anhydride” – and is continued according to the number of oxidations that the said nonmetal has.

When it has only one oxidation state, the “metal-element” is named “plus” after it.

On the other hand, if this element has two oxidation states, the “bear” or “ico” is placed at the end, when it uses its lower or higher valency, respectively.

If the nonmetal has an oxidation number of three, the minor is named with the prefix”hippo”and the suffix”oso”, the intermediate with the ending”oso”and the greater with the suffix”ico”.

When a non-metal has four oxidation states, the shortest of all is named with the prefix “hicc” and the suffix “bear”, the minor intermediate with the ending “bear”, the major intermediate with the suffix “ico and”. Above all with the prefix “per” and the suffix “echo”.

Summary rules for the names of nonmetal oxides

Regardless of the nomenclature used, always observe the oxidation (or valence) of each element in the oxide. The rules for their naming are summarized below:

first rule

If the non-metal presents a unique oxidation state, as in the case of boron (B 2 O 3 ), the compound is named as follows:

traditional nomenclature

Boron Anhydride.

arranged with prefixes

according to the number of atoms of each element; In this case, deborium trioxide.

Systematics with Roman Numerals

Boron oxide (this is omitted because it has a unique oxidation state).

second law

If a non-metal has two oxidation states, as is the case with carbon (+2 and +4, which yields oxides of CO and CO 2 , respectively), we name them as such:

traditional nomenclature

The endings “bear” and “ico” to indicate low and high valency, respectively (carbonase anhydride for CO and carbon dioxide for CO 2 ).

systematic naming with prefixes

Carbon monoxide and carbon dioxide.

Systematic Nomenclature with Roman Numerals

Carbon oxide (II) and carbon oxide (IV).

third law

If a non-metal has three or four oxidation states, it is named as follows:

traditional nomenclature

If the non-metal has three valves, proceed as described earlier. In the case of sulfur, they would be hyposulfuric anhydride, sulfur dioxide and sulfuric anhydride, respectively.

If a non-metal has three oxidation states, it is named the same way: hypochlorous anhydride, chlorine anhydride, chloric anhydride, and perchloric anhydride, respectively.

systematic nomenclature with prefixes or roman numerals

The same rules apply for compounds that have two oxidation states in their non-metal, receiving names similar to those.


–  They can be found in different states of aggregation.

The non –  metals that make up these compounds have high oxidation numbers.

–  Nonmetal oxides in the solid phase are usually of a brittle structure.

–  They are mostly molecular compounds, covalent in nature.

They are acidic in  nature and form oxidised compounds.

Its acidic character increases from left to right in the periodic  table.

–  They do not have good electrical or thermal conductivity.

–  These oxides have relatively low melting and boiling points compared to their native counterparts.

–  There are reactions with water to give rise to acidic compounds or alkaline species to produce salts.

When they react with the basic type of oxide, they produce oxoan salts 

Some of these compounds, such as sulfur or nitrogen oxides, are considered environmental pollutants 


Non-metallic oxides have a wide range of uses in the industrial sector and in laboratories and various fields of science.

Its uses include the manufacture of cosmetic products, such as flush or nail enamels, and the manufacture of ceramics.

They are also used in the improvement of paints, in the production of catalysts, in the manufacture of liquids in fire extinguishing or in aerosols, in propellant gas in food products, and are also used as an anesthetic in minor operations.


chlorine oxide

Two types of chlorine oxides are given. Chlorine (III) oxide is a dark colored solid that has highly explosive properties even at temperatures below the melting point of water (0 ° K).

On the other hand, chlorine oxide (VII) is a gaseous compound with corrosive and flammable properties that is obtained by mixing with some perchlorates of sulfuric acid.

silicon oxide

It is a solid also known as silica and is used in the manufacture of cement, ceramics and glass.

In addition, it can form different substances depending on its molecular order, originating from quartz when it is arranged crystals and opal when its arrangement is amorphous.

sulfur oxide

Sulfur dioxide is a colorless gas precursor to sulfur trioxide, while sulfur trioxide is a primary compound when sulfonation is performed, which leads to the manufacture of pharmaceuticals, dyes and detergents.

In addition, it is a contaminating agent of great importance, as it is present in acid rain.