- General formula of binary salts
- Nomenclature of binary salts
- Systematic nomenclature
- Stock nomenclature
- Traditional nomenclature
- How are binary salts formed?
- Examples of binary salts
- References
The binary salts are widely known in the chemical ionic species, identified as substances which are part of strong electrolytes, due to their dissociation completely into their constituent ions when they are in a solution.
The term "binary" refers to their formation, since they are composed of only two elements: a cation of metallic origin with a simple anion of non-metallic origin (other than oxygen), which are linked by an ionic bond.
NaCl, a binary salt
Although their name indicates that they are made up of only two elements, this does not prevent that in some of these salts there may be more than one atom of the metal, the nonmetal or both species. On the other hand, some of these species show quite toxic behavior, such as sodium fluoride, NaF.
They can also show high reactivity when in contact with water, although between chemically very similar salts these properties can vary enormously.
General formula of binary salts
As previously stated, binary salts are made up of a metal and a non-metal in their structure, so their general formula is M m X n (where M is the metallic element and X is the non-metallic element).
In this way, the metals that are part of the binary salts can be from the "s" block of the periodic table - alkaline (such as sodium) and alkaline earth (such as calcium) - or from the "p" block of the periodic table (like aluminum).
In the same way, among the non-metallic elements that constitute this type of chemical substances are those of group 17 of the periodic table, known as halogens (such as chlorine), as well as other elements of the “p” block such as sulfur or nitrogen, except for oxygen.
Nomenclature of binary salts
According to the International Union of Pure and Applied Chemistry (IUPAC), three systems can be used to name binary salts: systematic nomenclature, stock nomenclature and traditional nomenclature.
Systematic nomenclature
When using this method, you must begin with the name of the nonmetal, adding the ending –uro; for example, in the case of a bromine salt (Br) it would be named as "bromide".
Immediately after naming the nonmetal, the preposition "of" is placed; in the previous case it would be "bromide of".
Finally, the metallic element is named as it is normally called. Therefore, if the same example is followed and composed of potassium as the metal, the compound would be written as KBr (whose structure is balanced correctly) and is called potassium bromide.
In case the stoichiometry of the salt differs from the 1: 1 combination, each element is named using a prefix that indicates the subscript or number of times each one is found.
For example, the combination ratio in the CaCl 2 salt is 1: 2 (for every calcium atom there are two chlorine), so it is named as calcium dichloride; it is the same with the other compounds.
Stock nomenclature
When using this procedure, you start by naming the compound in a very similar way to how it is done in the systematic nomenclature, but without prefixing any component of the substance.
In this case, only the oxidation number of the metallic element (its absolute value in all cases) is taken into account.
To name the binary salt, place the valence number in Roman notation in parentheses, after the species name. FeCl 2 can be given as an example, which, according to these rules, is called iron (II) chloride.
Traditional nomenclature
When the rules of traditional nomenclature are followed, instead of adding some prefix to the anion or cation of the salt or explicitly placing the valence number of the metal, rather a suffix is placed depending on the oxidation state of the metal.
To use this method, the nonmetal is named in the same way as in the stock method and, if a salt is present whose elements have more than one oxidation number, it must be named using a suffix that indicates it.
In case the metallic element is using its lowest oxidation number, the suffix "bear" is added; On the other hand, if you use its highest valence number, the suffix "ico" is added.
An example of this might be the FeCl 3 compound, which is called “ferric chloride” because iron is using its maximum valence (3). In the FeCl 2 salt, in which iron uses its lowest valence (2), the name ferrous chloride is used. It happens in a similar way with the rest.
How are binary salts formed?
As mentioned previously, these substances of a mostly neutral nature are formed through the combination by an ionic bond of a metallic element (such as those in group 1 of the periodic table) and a non-metallic species (such as those of group 17 of the periodic table), except for oxygen or hydrogen atoms.
In the same way, it is common to find that in chemical reactions that involve binary salts there is a release of heat, which means that it is an exothermic reaction. In addition, there are various risks depending on the salt with which it is treated.
Examples of binary salts
Below are some binary salts along with their different names, depending on the nomenclature used:
NaCl
- Sodium chloride (traditional nomenclature)
- Sodium chloride (stock nomenclature)
- Sodium monochloride (systematic nomenclature)
BaCl 2
- Barium chloride (traditional nomenclature)
- Barium chloride (stock nomenclature)
- Barium dichloride (systematic nomenclature)
CoS
- Cobalt sulfide (raditional nomenclature)
- Cobalt (II) sulfide (stock nomenclature)
- Cobalt monosulfide (systematic nomenclature)
Co 2 S 3
- Cobalt sulfide (traditional nomenclature)
- Cobalt (III) sulfide (stock nomenclature)
- Dicobalt trisulfide (systematic nomenclature)
References
- Wikipedia. (sf). Binary phase. Recovered from en.wikipedia.org
- Chang, R. (2007). Chemistry, Ninth edition (McGraw-Hill).
- Levy, JM (2002). Hazmat Chemistry Study Guide, Second Edition. Recovered from books.google.co.ve
- Burke, R. (2013). Hazardous Materials Chemistry for Emergency Responders, Third Edition. Recovered from books.google.co.ve
- Franzosini, P., and Sanesi, M. (2013). Thermodynamic and Transport Properties of Organic Salts. Recovered from books.google.co.ve