- What are metal oxides?
- How are metal oxides obtained?
- Nomenclature of metal oxides
- Uses of metal oxides
- Importance of metal oxides
- Examples of metal oxides
- Non-metallic oxides
We explain what metal oxides are, how they are obtained, named and what they are used for. Also, what are non-metallic oxides.
What are metal oxides?
In chemistry, is called basic oxides or metal oxides to a type of compounds molecular molecules that result from combining a metal with oxygen. In these compounds the atom oxygen has oxidation state -2. Its general formula can be expressed as follows:
X2On
Where X is the metallic element and n is the Valencia of said metal.
These compounds are also called basic oxides because they react with water to form hydroxides, which is why they are also known as bases. These types of compounds are quite common in everyday life since chemical elements more abundant in the periodic table they are, precisely, the metallic ones.
Metal oxides retain some of the properties of the metallic element, such as the good conductivity of the electricity and the heat, or its elevated melting points. In addition, they are presented in all three states of matter aggregation.
How are metal oxides obtained?
Metal oxides, as we have said before, are obtained when any metal is reacted with oxygen. An example of this we see when a metal oxidizes by being in continuous contact with the oxygen present in the air or in the Water. This relationship is usually expressed in the following formula:
Oxygen (O) + Metallic element (X) = Basic or metallic oxide.
Nomenclature of metal oxides
There are different systems of chemical nomenclature. To name the metallic oxides we will use the stoichiometric or systematic system (recommended by the IUPAC) and the STOCK system. There is also a so-called “traditional” naming system, but it is rarely used today.
To name metal oxides according to these systems, some questions must first be taken into account:
- When the metallic element has a single oxidation number (for example, gallium (Ga) has only 3+):
- Traditional. Suffixes and prefixes are added according to the oxidation state of the metallic elements. For example: gallium oxide (Ga2O3).
- Systematic. They are named according to the number of atoms of each type that the molecule. For example: digalium trioxide (Ga2O3).
- STOCK. The oxidation state of the metal in that compound is added to the end of the name, in Roman numerals and in parentheses. Many times, if the metal has only one oxidation state, the Roman numeral is omitted. For example: gallium (III) oxide or gallium oxide (Ga2O3).
- When the metallic element has two oxidation numbers (for example, lead (Pb) has 2+ and 4+):
- Traditional. Add to suffixes Y prefixes according to the oxidation state of the metallic elements. When the element has the highest oxidation state the suffix -ico is used and when it has the lowest the suffix -oso is used. For example: lead oxide (PbO2) when the oxidation state is the highest (4+) and plumbic oxide (PbO) when the oxidation state is the lowest (2+).
- Systematic. Rules are upheld. For example: lead dioxide (PbO2), when it has an oxidation state (4+) and lead monoxide lead (PbO) when it has an oxidation state (2+).
- STOCK. The oxidation state of the metal in that compound is added to the end of the name as appropriate, in Roman numerals and in parentheses. For example: lead (IV) oxide (PbO2) and lead (II) oxide (PbO).
Clarification. Sometimes subscripts can be simplified. This is the case of lead (IV) oxide, which could be represented as Pb2O4, but the subscripts are simplified and PbO2 remains.
- When the metallic element has three oxidation numbers (for example, chromium (Cr) has mainly 2+, 3+, 6+):
- Traditional. Suffixes and prefixes are added according to the oxidation state of the metallic elements. When the element has the highest oxidation state the suffix -ico is added, for the intermediate oxidation state the suffix -oso is added and for the lowest oxidation the prefix -hypo is added, followed by the name of the metal, followed by the suffix -oso . For example: chromic oxide (CrO3) when it has an oxidation state (6+), chromic oxide (Cr2O3) when it has an oxidation state (3+) and hypochromic oxide (CrO) when it has an oxidation state (2+).
- Systematic. Rules are upheld. For example: chromium monoxide (CrO) when it has an oxidation state (2+), dichrome trioxide (Cr2O3) when it has an oxidation state (3+) and chromium trioxide (CrO3) when it has an oxidation state (6+) .
- STOCK. The oxidation state of the metal in that compound is added to the end of the name as appropriate, in Roman numerals and in parentheses. For example: chromium (II) oxide (CrO), chromium (III) oxide (Cr2O3) and chromium (VI) oxide (CrO3).
- When the element has four oxidation numbers (manganese (Mn) has mainly 2+, 3+, 4+, 7+)
- Traditional. When the element has the highest oxidation state, the prefix per- and the suffix -ico are added, for the oxidation state that follows the suffix -ico is added, for the following oxidation state the suffix -oso is added and for the lower oxidation state the prefix hypo- and the suffix -oso are added. For example: permanganic oxide (Mn2O7) when it has an oxidation state (7+), manganic oxide (MnO2) when it has an oxidation state (4+), manganous oxide (Mn2O3) when it has an oxidation state (3+) and hypomanganous oxide (MnO) when it has an oxidation state (2+).
- Systematic. Rules are upheld. For example: dimhanganese heptaoxide (Mn2O7) when it has oxidation state (7+), manganese dioxide (MnO2) when it has oxidation state (4+), dimanganese trioxide (Mn2O3) when it has oxidation state (3+) and manganese monoxide (MnO) when it has an oxidation state (2+).
- STOCK. The oxidation state of the metal in that compound is added to the end of the name as appropriate, in Roman numerals and in parentheses. For example: manganese (VII) oxide (Mn2O7), manganese (IV) oxide (MnO2), manganese (III) oxide (Mn2O3) and manganese (II) oxide (MnO).
Uses of metal oxides
Lead oxide is used in the manufacture of glass and crystal.
Metal oxides have a huge application in everyday life, especially in the manufacture of various chemical substances. Some examples are:
- Magnesium oxide. It is used for the preparation of drugs for the stomach, and in the manufacture of antidotes for intoxications.
- Zinc oxide. It is used for the manufacture of paintings, colorants and dyeing pigments.
- Aluminum oxide. Is used for alloys of enormous hardness and other metals of industrial use.
- Lead oxide It is used in the manufacture of glass.
Importance of metal oxides
Metal oxides are extremely important for the human being and for the industries contemporary, as they serve as an attachment in many compounds of daily application.
In addition, they are the raw material in chemical laboratories to obtain bases and other compounds, since their abundance makes them much easier to obtain and manipulate.
Examples of metal oxides
Some additional examples of metal oxides are:
- Sodium oxide (Na2O)
- Potassium oxide (K2O)
- Calcium oxide (CaO)
- Cupric oxide (CuO)
- Ferrous oxide (FeO)
- Lead oxide (PbO)
- Aluminum oxide (AlO3)
Non-metallic oxides
Oxides not metallic are those in which oxygen combines with a non-metallic element, and are known as anhydrides. The most common of them is the carbon dioxide (CO2) that we expel in the breathing and that the plants consume to perform the photosynthesis.
These compounds are very important in biochemistry. Unlike metallic ones, they are not good conductors of electricity and heat. When they are made to react with water they obtain acids, also called oxacids.