The term "base" is very common in the process of studying chemistry, both organic and inorganic. For the first time, scientists wondered: "What is the" base "in chemistry?" back in the 17th century. The result was the emergence of several theories of acids and bases, bearing the names of their founders. The definition of what is the "basis" of chemistry can be given by referring to the one that offers the best justification for this case.
Theories of Acids and Bases
Within the framework of this article, only parts of them will be considered that answer the question: “What is the“ base ”in chemistry?”
The most famous theories at the moment are four.
1. The theory of electrolytic dissociation of Arrhenius-Ostwald.
It is based on ideas about the decomposition of substances into ions in the aquatic environment. According to this theory, the bases are substances that, upon dissociation, form a hydroxide anion.
Its advantage is the ability to classify acids and bases by strength. The disadvantage is its applicability only to aqueous solutions and the impossibility of explaining the basic properties of substances not containing hydroxyl groups.
2. The Bronsted-Lowry Protolithic Theory.
In this case, the basis is a substance capable of attaching a proton (hydrogen cation). At the same time, the concept of amphotericity arises - the possibility of the presence of either acidic or basic properties of compounds depending on conditions. It does not separately discuss the basic and acidic properties. The main point of the theory - the substance becomes one or the other in the presence of another compound, depending on their nature. It is argued that acids and bases necessarily exist as pairs of compounds.
This theory is more general, explains the basic properties of compounds that do not have hydroxyl groups in the molecule, and also makes it possible to understand what a “base” is in organic chemistry. It was with the help of the Bronsted-Lowry theory that it was possible to explain the mechanism of action of acid-base indicators.
3. Electronic Lewis theory.
It is even more advanced. It explains the mechanism of proton migration described in the previous theory. Lewis argued that a base is a compound that can donor a free electron pair. An example of a Lewis base in chemistry is water, ammonia. The basicity of organic compounds is also largely due to this theory.
4. The generalized theory of Usanovich.
It is customary to operate with charges of particles. So, according to Usanovich, a base is a particle that can attach a proton or other cations, or give away an electron and other anions. Unfortunately, it does not describe nonionic processes. Usanovich’s theory has not been finalized. To this day, scientists are making attempts to bring it to its logical conclusion. It is expected that in this case it is Usanovich’s theory that will most accurately and correctly describe the nature of the acid-base properties of the compounds.
Currently, all four theories are used, depending on the systems in question.
What is the “base” in inorganic chemistry?
This question is easiest to answer using the electronic theory or the Arrhenius-Ostwald theory, since most reactions take place in aqueous solutions.
What is a “foundation”? Examples in inorganic chemistry: metal hydroxides, ammonia.
In the first case, in aqueous solutions, the molecules dissociate with the removal of the hydroxide anion. This is a vivid example of what a “foundation” is from the point of view of the Arrhenius theory.
The main properties of ammonia are better explained by the presence of a lone electron pair on the nitrogen atom, which corresponds to the Lewis theory.
In organic chemistry
What are the bases in chemistry? Examples of organic bases are representatives of the class of amines. The basicity of organic compounds is usually explained in terms of the Lewis theory. Like ammonia, the basic properties of amines are due to a lone electron pair located on the nitrogen atom.
Another example of a base in organic chemistry is the anions of carboxylic acids and alkoxyl (obtained by cleavage of a hydrogen atom from an alcohol group). These properties can be explained using the theory of Usanovich or Bronsted-Lowry.
Conclusion
So what is the “foundation” in chemistry? This substance is able to attach to itself cations of hydrogen or other elements. That is, theoretically, it can be any anion or molecule having an unshared electron pair on valence orbitals of at least one of the atoms.
It is customary to classify bases by nature (organic and inorganic), strength, acidity (the number of hydrogen cations that can be attached to one base molecule). They are of great importance in human life. Therefore, attempts to understand the nature of their properties even more deeply and fully are likely to be undertaken for a long time to come.