Inorganic chemistry deals with the synthesis and behavior of inorganic and organometallic compounds. This field encompasses all chemical compounds except the myriad of organic compounds (carbon-based compounds, which normally contain C-H bonds), which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, as there is much overlap in the subdiscipline of organometallic chemistry. It has applications in all aspects of the chemical industry, including catalysis, materials science, pigments, surfactants, coatings, medicines, fuels and agriculture.
Many inorganic compounds are ionic compounds, consisting of cations and ion-bonded anions. Examples of salts (which are ionic compounds) are magnesium chloride MgCl 2, which consists of Mg 2+ magnesium cations and Cl- chloride anions; O sodium oxide Na2O, which consists of Na + sodium cations and O2- oxide anions. In any salt, the proportions of the ions are such that the electric charges are cancelled out, so that the bulk compound is electrically neutral. The ions are described by their oxidation state and their ease of formation can be deduced from the ionization potential (for cations) or electron affinity (anions) of parent elements.
Important classes of inorganic compounds are oxides, carbonates, sulfates and halides. Many inorganic compounds are characterized by high melting points. Inorganic salts typically are poor conductors in the solid state. Other important features include its high meilting point and ease of crystallization. When some salts (for example NaCl) are very soluble in water, others (eg, SiO2) are not.
The simplest inorganic reaction is the double displacement when in the mixture of two salts the ions are exchanged without a change in the oxidation state. In redox reactions, one reactant, the oxidant, decreases its oxidation state and another reactant, the reductant, has its increased oxidation state. The net result is an electron exchange. The exchange of electrons can occur indirectly, for example, in batteries, a key concept in electrochemistry.
When a reactant contains hydrogen atoms, a reaction can take place by proton exchange in acid-base chemistry. In a more general definition, any chemical species capable of binding to electron pairs is called Lewis acid; In contrast, any molecule that tends to donate a pair of electrons is known as a Lewis base. As a refinement of acid-base interactions, the HSAB theory takes into account the polarizability and size of the ions.
Inorganic compounds are found in nature as minerals. The soil may contain iron sulfide such as pyrite or calcium sulfate as gypsum. Inorganic compounds are also found multitasking as biomolecules: as electrolytes (sodium chloride), energy storage (ATP) or construction (the polyphosphate backbone in the DNA).
The first important artificial inorganic compound was ammonium nitrate for soil fertilization through the Haber process. The inorganic compounds are synthesized for use as catalysts such as vanadium (V) oxide and titanium (III) chloride, or as organic chemistry reagents such as lithium aluminum hydride.
Subdivisions of inorganic chemistry are organometallic chemistry, cluster chemistry and bioinorganic chemistry. These fields are active areas of research in inorganic chemistry, directed towards new catalysts, superconductors and therapies.