Anomalous Behaviour of Carbon

Carbon is a chemical element with a strong reactivity. It can react with a wide variety of other elements to form an infinite number of compounds. Carbon-based compounds outnumber all other element-based molecules. Carbon is a family of elements that consists of the following components:

• Carbohydrates (C)
• Silicon (Si)
• Germanium (Ge)
• Tin (Sn)
• Lead (Pb)

Methane (CH4) is the most fundamental or universal form of carbon. Hydrocarbons are a family of chemicals formed by the reaction of hydrogen and carbon. By simply adding hydrogen to the carbon atoms’ valency, one can readily determine the chemical formula of such compounds.

Six hydrogen atoms are necessary to match the valency of each carbon atom in ethane, which has two carbon atoms (while noting that a single bond exists between both the carbon atoms). As a result, ethane has the chemical formula C2H6. In the synthesis of a molecule, a single, double, or even triple bond can now be created between two or more carbon atoms.

Carbon compounds are categorised into two broad categories based on the number of bonds formed between the carbon atoms: saturated and unsaturated carbon compounds.

Two Classifications of Carbon Compounds

1. Saturated Carbon Compounds

These are compounds in which the carbon atoms are connected by only single bonds in a chain or ring. Alkanes are the most frequent saturated chain carbon compounds. The chemical structure of ethane is a member of the alkane family.

2. Unsaturated Carbon Compounds

These are compounds in which carbon atoms are connected via double or triple bonds in a chain or ring. Alkenes (in which carbon atoms are linked by double bonds) and alkynes are the most common unsaturated chain carbon compounds (here carbon atoms get linked through triple bonds). Ethene is an alkene.

Anomalous Behaviour 

Carbon is the first element in Group 14 members. It exhibits anomalous behaviour, which means that its properties are distinct from those of the other Carbon family members. The fundamental explanation for carbon’s unusual features is as follows:

• Extremely tiny atomic size
• Increased electronegativity
• Increased ionisation enthalpy
• Absence of the Valence shell d orbital

Anomalous Properties of Carbon 

Carbon, like boron, exhibits abnormal features. Carbon has the greatest melting and boiling points of any member of group 14. As we progress along with the group, melting and boiling points tend to fall.

The following are the primary differences seen in the Carbon element:

Tetravalency Of Carbon

Carbon possesses tetravalency, which means it can share four electrons to complete its octet, enabling it to form bonds with four monovalent atoms. Carbon may combine with oxygen, nitrogen, hydrogen, and halogens to form a diverse range of compounds with distinct characteristics and properties.

Its valence shell can only accommodate four pairs of electrons, as only s and p orbitals are available. As a result, the covalence can be limited to four, although other members of the group have a larger covalence due to the presence of the d-orbital.

Electronic configuration

Carbon’s electrical arrangement is 1s2, 2s2, 2p2. Carbon has a valency of four, indicating that it possesses tetravalency and is capable of forming bonds with four distinct elements. In other words, because carbon has only four valence orbitals, it can only contain a maximum of four electron pairs. As a result, its maximum covalency is four, whereas other Group 14 elements can reach six due to the presence of an empty d-orbital.

CH4 (methane) is an organic molecule composed of one carbon atom and four hydrogen atoms that share electrons. Carbon shares one of its four electrons with each hydrogen atom to form four covalent bonds.

Catenation

Catenation is another critical characteristic of carbon. It is defined as the capacity of comparable or similar atoms to form covalent connections. In other words, carbon atoms form extensive carbon chains when they come together. This chain can span up to 70-80 carbon atoms. As a result of this reaction, exceedingly complex compounds having a straight carbon chain, a branched carbon chain, or a ring carbon chain are created. Saturated hydrocarbons are carbon molecules that include only one carbon-carbon bond, while unsaturated hydrocarbons contain two carbon-carbon links.

Catenation is largely determined by the binding energy of elements. Due to the high binding energy of the carbon-carbon covalent bond, it is capable of forming a long chain molecule.

Electronegativity

Electronegativity refers to an atom’s ability to attract a shared pair of electrons in a covalent bond. Carbon has a high proclivity for forming p-p multiple bonds with other elements such as nitrogen, oxygen, and sulphur. The other elements do not form p-p bonds because their atomic orbitals are too wide and diffused to overlap effectively. On the other hand, due to the presence of d-orbitals, they tend to form d-d bonds. Additionally, as the size of d-orbitals grows down the group, from Si to Pb, this tendency to form d-d bonds reduces.

Small Size of Carbon

Carbon’s small size also plays a role in the bulk of its properties. Due to their small size, carbon-based compounds are exceedingly stable. The carbon atom’s tiny size facilitates the creation of numerous bonds and also contributes to the catenation feature. Carbon is a half-filled element with four electrons in its outermost shell. This configuration enables the nucleus to contain both bonded and unbonded electrons, which makes it stable.

Allotropic forms

Due to their catenation property, carbon atoms can exist in four different allotropes: diamond, graphite, lead, and Buckminsterfullerene. In comparison to the rest of Group 14, carbon in the form of diamond (an allotrope of Carbon) is particularly difficult to work with.

To recapitulate, carbon’s tetravalency, small size, and catenation properties set it apart from other elements, and a significant portion of chemistry is devoted to the study of this type of chemical.

Conclusion

Carbon is a member of the periodic table’s group 14. It has been known in the form of graphite, diamond, coal, and charcoal since very early times. It is a necessary component of all biological systems. Carbon can be found in a wide number of compounds. Carbon compounds can be classified into two types: inorganic and organic compounds. Carbon’s atypical behaviour is explained by its short atomic size, increased electronegativity, and the absence of unoccupied d orbitals in its valence shell.