Inorganic compound
A chemical compound that lacks carbon–hydrogen bonds, studied in inorganic chemistry.
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An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds—that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as inorganic chemistry. These compounds make up the vast majority of the Earth's crust, though the precise compositions of the deep mantle remain an active area of scientific investigation. Importantly, the classification of a compound as inorganic does not preclude its presence in living organisms; many such substances are normal components of biological systems.
The historical distinction between inorganic and organic chemistry was once rooted in vitalism, the belief that organic compounds required a "vital spirit." This view was challenged in 1828 when Friedrich Wöhler converted ammonium cyanate into urea, an event often cited as the starting point of modern organic chemistry. In the absence of vitalism, the boundary between the two fields is now understood to be largely semantic.
In modern usage, definitions vary. The Inorganic Crystal Structure Database (ICSD) defines inorganic carbon compounds as those that may contain either carbon-hydrogen or carbon-carbon bonds, but not both.
The book series Inorganic Syntheses does not formally define the term, though its content focuses heavily on metal complexes with organic ligands. The International Union of Pure and Applied Chemistry (IUPAC) does not define "inorganic compound" but defines an inorganic polymer as having a skeletal structure that does not include carbon atoms. Certain carbon-containing substances are routinely considered inorganic, including all allotropes of carbon (such as graphite, diamond, buckminsterfullerene, and graphene), carbon monoxide, carbon dioxide, carbides, and salts of inorganic anions like carbonates, cyanides, cyanates, thiocyanates, and isothiocyanates.
Lore & Background
Inorganic compounds comprise most of the Earth's crust, although the compositions of the deep mantle remain active areas of investigation. All allotropes of carbon and some simple carbon compounds are often considered inorganic. Examples include the allotropes of carbon (graphite, diamond, buckminsterfullerene, graphene, etc.), carbon monoxide, carbon dioxide, carbides, and salts of inorganic anions such as carbonates, cyanides, cyanates, thiocyanates, isothiocyanates, etc. Many of these are normal parts of mostly organic systems, including organisms; describing a chemical as inorganic does not necessarily mean that it cannot occur within living things.
Reader's Guide
Inorganic compounds are chemical substances that typically lack carbon-hydrogen bonds, distinguishing them from organic compounds, and their study falls under inorganic chemistry. They constitute the majority of the Earth’s crust, though the exact composition of the deep mantle remains an active research area. Certain carbon-containing substances, such as all allotropes of carbon (including diamond, graphite, and graphene), carbon monoxide, carbon dioxide, carbides, and salts like carbonates and cyanides, are commonly classified as inorganic. Importantly, describing a compound as inorganic does not preclude its presence in living organisms, as many such compounds occur naturally within biological systems.
Historically, the 1828 conversion of ammonium cyanate into urea by Friedrich Wöhler is often regarded as a pivotal moment in chemistry, as it challenged the then-prevalent belief that organic compounds required a “vital spirit.” With the decline of vitalism, the distinction between inorganic and organic chemistry became largely a matter of convention. In modern usage, definitions vary: the Inorganic Crystal Structure Database (ICSD) allows inorganic carbon compounds to contain either C-H or C-C bonds, but not both. The series Inorganic Syntheses does not formally define inorganic compounds, though it primarily features metal complexes with organic ligands. IUPAC provides no definition for “inorganic compound” but defines an inorganic polymer as having a skeletal structure lacking carbon atoms.
Did You Know?
- In Wöhler's era, there was widespread belief that organic compounds were characterized by a vital spirit.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Inorganic compound (CC BY-SA 4.0).
- Word definitions: the Codexery glossary, each quoted from its Wikipedia article.
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