Definition of Inorganic Compounds
Inorganic compounds are typically the chemical compound that lacks carbon-hydrogen bonds, that is, a compound that is not an organic compound.
Inorganic compounds comprise most of the Earth’s crust, although the compositions of the deep mantle remain active areas of investigation. Some simple compounds that contain carbon are often considered inorganic.
Examples include carbon monoxide, carbon dioxide, carbides, and the following salts of inorganic cations: carbonates, cyanides, cyanates, and thiocyanates. Many of these are normal parts of mostly organic systems, including organisms; describing a chemical as inorganic does not necessarily mean that it does not occur within living things.
Inorganic compounds include compounds made up of two or more elements other than carbon and certain carbon-containing compounds that lack carbon-carbon bonds, such as cyanides and carbonates.
Inorganic compounds are most often classified in terms of the elements or groups of elements that they contain. Oxides, for example, can be either ionic or molecular. Ionic oxides contain O2- (oxide) ions and metal cations.
Whereas molecular oxides contain molecules in which oxygen (O) is covalently bonded to other nonmetals such as sulfur (S) or nitrogen (N).
When ionic oxides are dissolved in water, the O2- ions react with water molecules to form hydroxide ions (OH–), and a basic solution results.
Molecular oxides react with water to produce oxyacids, such as sulfuric acid (H2SO4) and nitric acid (HNO3). In addition, inorganic compounds include hydrides (containing hydrogen atoms or H– ions), nitrides (containing N3- ions), phosphides (containing P3- ions), and sulfides (containing S2- ions).
Transition metals form a great variety of inorganic compounds. The most important of these are coordination compounds in which two to six ligands surround the metal atom or ion. Ligands are ions or neutral molecules with electron pairs that can donate to the metal atom to form a coordinate covalent bond.
The resulting covalent bond is given a special name because one entity (the ligand) furnishes both of the electrons that are subsequently shared in the bond.
An example of a coordination compound is [Co(NH3)6 ] Cl3, which contains the Co(NH3)63+ ion, a cobalt ion (Co3+) with six ammonia molecules (NH3) attached to it, acting as ligands.
Carbon compounds such as carbides (e.g., silicon carbide [SiC2]), some carbonates (e.g., calcium carbonate [CaCO3]), some cyanides (e.g., sodium cyanide [NaCN]), graphite, carbon dioxide, and carbon monoxide are classified as inorganic.
Inorganic Compounds Examples
- H2O – Water is a simple inorganic compound, even though it contains hydrogen, a key atom (along with carbon) in many organic compounds. The atoms in a molecule of water have formed very simple bonds due to this lack of carbon.
- HCl – Hydrochloride, also known as hydrochloric acid when it is dissolved in water, is a colorless, corrosive acid with a fairly strong pH. It is found in the gastric juices of many animals, helping in digestion by breaking down food.
- CO2 – Carbon dioxide, despite the presence of a carbon atom in the formula, is classified as an inorganic compound. This has causeda dispute within the scientific community, with questions being raised as to the validity of our current methods of classifying compounds. Currently, organic compounds contain a carbon or a hydrocarbon, which forms a stronger bond. The bond formed by carbon in CO2 is not a strong bond.
- NO2 – Nitrogen dioxide gas presents a variety of colors at different temperatures. It is often produced in atmospheric nuclear tests, and is responsible for the tell-tale reddish color displayed in mushroom clouds. It is highly toxic, and forms fairly weak bonds between the nitrogen and oxygen atoms.
- Fe2O3 – Iron (III) oxide is one of the three main oxides of iron, and is an inorganic compound due to the lack of a carbon atom or a hydrocarbon. Iron (III) oxide occurs naturally as hematite, and is the source of most iron for the steel production industry. It is commonly known asrust, and shares a number of characteristics with its naturally occurring counterpart.
Friedrich Wohler’s conversion of ammonium cyanate into urea in 1828 is often cited as the starting point of modern organic chemistry.
In Wohler’s era, there was a widespread belief that a vital spirit characterized organic compounds. In the absence of vitalism, the distinction between inorganic and organic chemistry is merely semantic. One of the predominant theories in the early centuries is vitalism.
According to this theory, living things had a sort of a vital force –vis-vitalis – .That made them distinct from non-living things. This vital force enabled them to produce certain chemicals that non-living things would not be able to produce.
The chemicals that living things produced had been called organic since they came from organisms. Those that were obtainable from non-living things had been called inorganic, meaning “not organic”.
This was the fundamental boundary that defined organic from inorganic compounds. Inorganic compounds were thought of as compounds that were not derived from organisms. They may be derived, for instance, from geological systems, e.g. sediments and ores.
This belief had long been held for many centuries until Friedrich Wohler (1800 – 1882) disputed it with empirical evidence from his experiments.
In one of his experiments, he found out that urea, which was once thought to be produced only by living things, could be produced from inorganic precursors.
He discovered in 1828 that urea could be chemically produced from salts potassium cyanate and ammonium sulfate. This is considered a crucial turning point that later led to the rise of modern organic chemistry.
Types of Inorganic Compounds
- A chemical compound consists of atoms or ions of two or more elements that are chemically bonded together. Whereas a chemical element is a substance of only one type of atom. Most elements are inorganic but technically are not inorganic compounds since they comprise only one type of atom. Thus, the classification of inorganic compounds entails grouping substances comprised of more than one type of atom. Conversely, simple inorganic substances (not necessarily compounds) are typified as either metal or non metal. However, there is no clear distinction between metals and non-metals.
- Most inorganic compounds are ionic compounds. This means that the chemical bond that holds the atoms together is ionic. Based on inorganic compound constituents, ionic compounds could be classified into bases, acids, and salts. The ionic bond is the bond where there is a complete transfer of an electron from one atom to another. It is an electrostatic attraction between oppositely charged ions, i.e. cation and anion. A cation is a positively charged ion, whereas an anion is a negatively charged ion. For instance, sodium chloride is an ionic compound where the cation Na+ and the anion Cl– are held together by an ionic bond. An ionic compound that has hydrogen ions (H+) is classified as an acid. Conversely, an ionic compound with hydroxide (OH–) or oxide (O2–) is classified as a base. An ionic compound formed by acid-base reactions and without those ions is called a salt. Water is definitely one of the most important inorganic compounds to all living things. It is a compound comprised of two hydrogen atoms and one oxygen atom. However, it is not an ionic compound but a molecule held by covalent bonding between hydrogen and oxygen.