- How are they formed?
- Nomenclature
- Systematic nomenclature with Roman numerals
- Systematic nomenclature with prefixes
- Traditional nomenclature
- Summary rules for naming non-metallic oxides
- First rule
- Traditional nomenclature
- Systematics with prefixes
- Systematics with Roman numerals
- Second rule
- Traditional nomenclature
- Systematic nomenclature with prefixes
- Systematic nomenclature with Roman numerals
- Third rule
- Traditional nomenclature
- Systematic nomenclature with prefixes or Roman numerals
- Properties
- Applications
- Examples
- Chlorine oxide
- Silicon oxide
- Sulfur oxide
- References
The non - metal oxides also are called oxides acids which 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 acids H 2 SO 3 and HOCl, respectively.
Non-metallic oxides are of the covalent type, unlike metallic oxides that represent ionic oxides. Oxygen has the ability to form bonds with a huge number of elements due to its electronegative capacity, making it an excellent base for a wide variety of chemical compounds.
Quartz, can be generated from silicon oxide, a non-metallic oxide
Among these compounds there is the possibility that the oxygen dianion binds to a metal or non-metal to form an oxide. Oxides are common chemical compounds in nature, which have the characteristic of having at least one oxygen atom attached to another element, metallic or non-metallic.
This element occurs in a solid, liquid or gaseous state of aggregation, depending on the element to which the oxygen is attached and its oxidation number.
Between one oxide and another, even when oxygen is bound to the same element, there can be great differences in their properties; therefore they must be fully identified to avoid confusion.
How are they formed?
As explained above, acidic oxides are formed after the union of a non-metallic cation with a dianion of oxygen (O 2-).
This type of compound is observed in the elements located to the right of the periodic table (metalloids usually generate amphoteric oxides), and in transition metals in high oxidation states.
A very common way to form a non-metallic oxide is through the decomposition of ternary compounds called oxacids, which are made up of a non-metallic oxide and water.
It is for this reason that non-metallic oxides are also called anhydrides, since they are compounds that are characterized by having lost a water molecule during their formation.
For example, in the decomposition reaction of sulfuric acid at high temperatures (400 ºC), H 2 SO 4 decomposes to the point of completely becoming SO 3 and H 2 O vapor, according to the reaction: H 2 SO 4 + Heat → SO 3 + H 2 O
Another way to form non-metallic oxides is through the direct oxidation of the elements, as in the case of sulfur dioxide: S + O 2 → SO 2
It also happens in the oxidation of carbon with nitric acid to form carbon dioxide: C + 4HNO 3 → CO 2 + 4NO 2 + 2H 2 O
Nomenclature
To name the non-metallic oxides, several factors must be taken into account, such as the oxidation numbers that the non-metallic element involved may have and its stoichiometric characteristics.
Its nomenclature is similar to that of basic oxides. Furthermore, depending on the element with which oxygen combines to form the oxide, the oxygen or the 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
To name oxides of this type using the old Stock nomenclature (systematic with Roman numerals), the element to the right of the formula is named first.
If it is the non-metallic element, the suffix “uro” is added, then the preposition “de” and ends up naming the element on the left; if it is oxygen, start with "oxide" and name the element.
It is finished by placing the oxidation state of each atom followed by its name, without spaces, in Roman numerals and between parentheses; in case of having only one valence number, this is omitted. It only applies to elements that have positive oxidation numbers.
Systematic nomenclature with prefixes
When using the systematic nomenclature with prefixes, the same principle is used as in the Stock type nomenclature, but no Roman numerals are used to indicate the oxidation states.
Instead, the number of atoms of each should be indicated by the prefixes "mono", "di", "tri", and so on; It should be noted that if there is no possibility of confusing a monoxide with another oxide, this prefix is omitted. For example, for oxygen, "mono" is omitted from SeO (selenium oxide).
Traditional nomenclature
When the traditional nomenclature is used, the generic name is placed first - which in this case is the term "anhydride" - and continues according to the number of oxidation states that the non-metal possesses.
When it has only one oxidation state, it is followed by the preposition "of" plus the name of the non-metallic element.
On the other hand, if this element has two oxidation states, the ending "bear" or "ico" is given when it uses its lower or higher valence, respectively.
If the nonmetal has three oxidation numbers, the smallest is named with the prefix “hiccup” and the suffix “bear”, the intermediate with the ending “bear” and the largest with the suffix “ico”.
When the nonmetal has four oxidation states, the lowest of all is named with the prefix "hypo" and the suffix "bear", the minor intermediate with the ending "bear", the major intermediate with the suffix "ico" and the highest of all with the prefix “per” and the suffix “ico”.
Summary rules for naming non-metallic oxides
Regardless of the nomenclature used, the oxidation states (or valence) of each element present in the oxide must always be observed. The rules for naming them are summarized below:
First rule
If the non-metal has a single oxidation state, as is the case with boron (B 2 O 3), this compound is named like this:
Traditional nomenclature
Boron anhydride.
Systematics with prefixes
According to the number of atoms of each element; in this case, diboron trioxide.
Systematics with Roman numerals
Boron oxide (since it has only one oxidation state, this is ignored).
Second rule
If the non-metal has two oxidation states, as is the case of carbon (+2 and +4, which give rise to the oxides CO and CO 2, respectively), they are named as follows:
Traditional nomenclature
Endings "bear" and "ico" to indicate lower and higher valence, respectively (carbonaceous anhydride for CO and carbon dioxide for CO 2).
Systematic nomenclature with prefixes
Carbon monoxide and carbon dioxide.
Systematic nomenclature with Roman numerals
Carbon (II) oxide and carbon (IV) oxide.
Third rule
If the nonmetal has three or four oxidation states, it is named like this:
Traditional nomenclature
If the nonmetal has three valences, proceed as previously explained. In the case of sulfur, they would be hypo-sulfur anhydride, sulfur anhydride and sulfur anhydride, respectively.
If the non-metal has three oxidation states, it is named in the same way: hypochlorous anhydride, chlorous anhydride, chloric anhydride and perchloric anhydride, respectively.
Systematic nomenclature with prefixes or Roman numerals
The same rules used for compounds in which their nonmetal has two oxidation states apply, obtaining names very similar to those.
Properties
- They can be found in various states of aggregation.
- The non-metals that make up these compounds have high oxidation numbers.
- Non-metallic oxides in solid phase generally have a brittle structure.
- Most of them are molecular compounds, covalent in nature.
- They are acidic in nature and form oxacid compounds.
- Its acid character increases from left to right in the periodic table.
- They do not have good electrical or thermal conductivity.
- These oxides have relatively lower melting and boiling points than their basic counterparts.
- They have reactions with water to give rise to acidic compounds or with alkaline species to give rise to salts.
- When they react with basic type oxides, they give rise to oxoanion salts.
- Some of these compounds, such as sulfur or nitrogen oxides, are considered environmental pollutants.
Applications
Non-metallic oxides have a wide range of uses, both in the industrial field and in laboratories and in different fields of science.
Its uses include the creation of cosmetic products, such as blushes or nail polishes, and the manufacture of ceramics.
They are also used in the improvement of paints, in the production of catalysts, in the formulation of the liquid in fire extinguishers or the propellant gas in aerosol food products, and are even used as an anesthetic in minor operations.
Examples
Chlorine oxide
There are two types of chlorine oxide. Chlorine (III) oxide is a dark brown solid substance 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 combining sulfuric acid with some of the perchlorates.
Silicon oxide
It is a solid that is also known as silica and is used in the manufacture of cement, ceramics and glass.
Furthermore, it can form different substances depending on their molecular arrangement, giving rise to quartz when it is ordered crystals and opal when its arrangement is amorphous.
Sulfur oxide
Sulfur dioxide is a colorless precursor gas for sulfur trioxide, while sulfur trioxide is a primary compound when sulfonation is carried out, which leads to the manufacture of pharmaceuticals, colorants and detergents.
In addition, it is a very important pollutant, as it is present in acid rain.
References
- Wikipedia. (sf). Acidic Oxides. Retrieved from en.wikipedia.org
- Britannica, E. (nd). Nonmetal Oxides. Retrieved from britannica.com
- Roebuck, CM (2003). Excel HSC Chemistry. Recovered from books.google.co.ve
- BBC. (sf). Acidic Oxide. Retrieved from bbc.co.uk
- Chang, R. (2007). Chemistry, Ninth edition. Mexico: McGraw-Hill.