Catenation

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Define Catenation?

Catenation meaning or the catenation in chemistry is defined as a chemical linkage into the chains of atoms of a similar element, by only occurring among the atoms of an element, which contains a valence of at least two and that produces the relatively strong bonds with itself. This property is significant among the silicon and sulfur atoms, predominant among the carbon atoms, and slightly present among the atoms of nitrogen, germanium, tellurium, and selenium.


Occurrence

Carbon

Catenation takes place most readily with the carbon atoms, which produces the covalent bonds with the other carbon atoms to form structures and longer chains. This is the main reason for the presence of a huge number of organic compounds in nature. Carbon is well-known for its catenation properties, with organic chemistry importantly being the study of catenated carbon structures (also referred to as catenae). In biochemistry, carbon chains combine any of the different other elements, such as oxygen, biometals, and hydrogen, onto the backbone of carbon.

But, by no means carbon is described as the only element that is capable of forming such catenae, and the many other main-group elements are capable of producing an expansive range of catenae, including boron, hydrogen, phosphorus, sulfur, and silicon.

The element's ability to catenate is essentially determined by its bond energy to itself, which decreases as more dispersed orbitals (those with a higher azimuthal quantum number) overlap to form the bond. As a consequence, the carbon element, which has the least or minimal diffuse valence shell p-orbital, will form the longer p-p sigma bound chains of atoms compared to the heavier elements, which have higher valence shell orbitals.

The ability to catenate is influenced further by a combination of electronic and steric influences, such as the element's electronegativity, the molecular orbital n, and the ability to form different forms of covalent bonds. For the carbon atom, the sigma overlap between the adjacent atoms is strong enough that perfectly stable chains are formed. With the other elements, this was once thought to be not easier despite plenty of evidence to the contrary.


Hydrogen

The structure of the water theories involves the 3-dimensional networks of both chains and rings, and tetrahedra, which are linked via hydrogen bonding.

A polycatenated network, with the rings produced from metal-templated hemispheres, which are linked by the hydrogen bonds, was reported in 2008.

In organic chemistry, hydrogen bonding is well known to facilitate the formation of chain structures. For example, 4-tricyclanol C10H16O represents catenated hydrogen bonding between the hydroxyl groups by leading to the production of helical chains; crystalline isophthalic acid - C8H6O4 is built up from the molecules, which are connected by the hydrogen bonds, forming infinite chains.

Whereas in the unusual conditions, a one-dimensional series of hydrogen molecules confined within a single wall, the carbon nanotube can be expected to become metallic at relatively low pressure, at 163.5 GPa. This is up to 40% of the ~400 GPa thought to be needed to metalize the ordinary hydrogen, a pressure that can be difficult to access experimentally.


Silicon

Silicon forms the sigma bonds to other silicon atoms (where the disilane is given as the parent of this compounds’ class). But, it is not easy to prepare and isolate SinH2n+2 (which is analogous to the saturated alkane hydrocarbons) with n greater than up to 8, as their thermal stability decreases with the increases in the number of silicon atoms. Silanes, which are higher in molecular weight compared to the disilane, decompose to hydrogen and polymeric polysilicon hydride. However, with the suitable pair of the organic substituents on each and every silicon in the place of hydrogen, it is also possible to prepare polysilanes (at times, the erroneous ones are referred to as polysilanes) that can be defined as the analogues of alkanes. These particular long-chain compounds contain surprising electronic properties - of high electrical conductivity, for example, arising from the sigma delocalization of electrons present in the chain.

Even the pi bonds of silicon-silicon are possible. But, these bonds are less stable compared to the carbon analogues. Disilane is quite reactive than ethane. Disilynes and disilene are quite rare, unlike alkynes and alkenes. Examples of disilynes are the long thought to be too unstable to be isolated, which were reported in 2004.


Example of Catenation

Most of the common examples of elements or catenation that exhibit catenation is given as follows:

  • Carbon

  • Silicon

  • Sulfur

  • Boron

Catenation takes place most readily in carbon by forming the covalent bonds to produce longer structures and chains with the other carbon atoms. This is the reason the huge number of organic compounds are found in nature. In organic chemistry, carbon is the best-known element for its catenation properties, with the analysis of catenated carbon structure.

By no means carbon is the only element capable of forming such catenae; however, and many other main group elements are capable of producing a wide range of catenae, including sulfur, boron, and silicon.


FAQ (Frequently Asked Questions)

1. Explain the catenation Property in Group 4

All the elements of the group 4 family or carbon family exhibit the catenation property. The first member of this family contains the highest tendency to catenate.


The tendency to catenate is given as follows:

C > Si > Ge > Sn > Pb


The tendency of catenation decreases down the group. This occurs due to the reason the atomic size increases down the group, and also, the strength of the covalent bond decreases. Thus, the catenation property gets decreased down the group.


2. What are Semi-Metallic elements?

In recent years, a number of double and triple bonds between semi-metallic elements such as germanium, silicon, bismuth, arsenic, and others have been published. The ability of such primary group elements to catenate is the research subject into inorganic polymers currently.

3. Why does carbon exhibit a catenation property?

The catenation property of the carbon atom is greater compared to the other elements. Therefore, its bond with the other carbon atom is quite stronger as the shared pair of electrons is quite closer to the nucleus. Therefore, the catenation property is shown by carbon

4. Give the importance of carbon’s catenation?

Catenation is defined as the linkage of atoms of a similar element into the longer chains. Catenation takes place most readily in carbon, which produces covalent bonds with the other carbon atoms to produce longer structures and chains. This is the main reason for the presence of a huge number of organic compounds in nature.