Valency of Carbon

One atom of carbon can form four covalent bonds as the carbon has a valency of four. Valency can be defined as the element's combining power when it forms other chemical molecules or compounds. Thus, carbon's tetravalency refers to its ability to bond with four other carbon atoms from other elements. Carbon is a versatile element that can form covalent bonds with other elements such as hydrogen, sulphur, oxygen, chlorine, and nitrogen. Carbon can also form compounds with double and triple bonds between carbon atoms. These carbon chains could be straight, branched, or in the form of rings.

What is the valency of Carbon?

An element's valency describes how well it can combine with other atoms to form chemical compounds or molecules. In this situation, carbon has a valence of four because it contains four valence electrons. To achieve the noble gas configuration, carbon forms four covalent bonds and shares its valence electrons. Carbon has a valency of four. The exterior electronic configuration of a carbon is 2S2 and 2P2.

Carbon has established its importance among the other elements due to its unique properties. Carbon's important properties are as follows:

• Catenation
• Tetravalency
• Size of a carbon atom

Organic compounds are defined as compounds that contain covalently bonded carbon atoms in their molecules and can exist in solid, liquid, or gaseous states. Let's look at how carbon's tetravalent nature affects carbon compounds.

Why is the Valency of Carbon 4?

Carbon has a valency of four because it has four electrons in its outermost shell and thus requires four more electrons to complete its octet configuration.

• Carbon has an atomic number of 6
• Carbon electronic configuration = 2, 4 = 1s2 2s2 2p2 = [He] 2s2 2p2

Because the outermost cells have four electrons, the carbon atom cannot lose or gain four electrons because it requires a large amount of energy. As a result, carbon atoms share their four electrons with other atoms. Because the electron is shared and the number of electrons shared is four. As a result, the valency of carbon is = 4, and thus "Carbon is Tetravalent."

Carbon cannot give or receive electrons; it can only share them. Many of the compounds it forms are affected by its tetravalent nature (4 valency of carbon).

Read More About: Versatile Nature of Carbon

Hybridization of Carbon

The process of combining atomic orbitals to create new hybrid orbitals suitable for representing bonding qualities is known as hybridization. Hybridised orbitals are useful in characterising the form of molecular orbitals, in addition to being an important aspect of valence bond theory. The atomic orbitals that contribute to hybridization are known as hybrid orbitals. One s-orbital and three p-orbitals on the carbon atom, for example, form a set of sp3 orbitals in methane, which has the chemical formula CH4. These orbitals are aimed at the four hydrogen atoms at the vertices of a typical tetrahedron.

In ethene, a double bond exists between the carbon atoms (C2H4). The carbon in this case is hybridised by sp2. The 2s orbital combines with two of the three 2p orbitals available in sp2 hybridization, yielding a total of three sp2 orbitals and one p-orbital. By overlapping two sp2 orbitals in ethane, two carbon atoms form a sigma bond, and each carbon atom forms two covalent connections with hydrogen by overlapping all s-sp2 with 120o angles. The pi connection between the carbon atoms is formed by a 2p-2p overlap. Experiments show that the hydrogen-carbon bonds are of comparable length and strength.

Many bonds exist between non-similar atoms as well. When two oxygen atoms are brought close to opposite sides of a carbon atom in CO2, one of the p orbitals on each oxygen forms a pi bond with one of the carbon's p-orbitals. The sp hybridization forms two double bonds in this case.

sp2 Hybridization

It is known to be sp2 hybridised when three equivalent orbitals are formed by combining one s and two p orbitals from the same shell of an atom. The sp2 hybridised orbitals form a flat triangular arrangement with a 120° angle between bonds in this case.

• Ethene is an example of sp2 hybridization (C2H4).
• In Ethene (C2H4), a single carbon atom forms three sigma bonds and one pi bond.
• Because carbon has three sigma bonds, it will combine two of its valence orbitals to form three identical orbitals.
• The hybridization is known as sp2 hybridised orbitals when the carbon atom is bound to three atoms.
• This hybridised orbital repels each other equally, resulting in the linear shape of sp hybridised carbon in ethene (C2H4) and a flat triangular arrangement with a 120° angle between bonds.

Valency of Carbon and Its Compounds - Alkane

An alkane has single bonds between its carbon atoms. The simplest alkane with more than one carbon atom is ethane C2H6. Each carbon has three hydrogens attached to it and is held together by a single bond. As a result, each carbon in the alkane has one carbon bond and three hydrogen bonds, for a total of four valencies.

Valency of Carbon and its Compounds - Alkyne

Three bonds connect the carbon atoms in an alkyne. Ethyne, also known as acetylene C2H2, is an alkyne molecule that contains more than one carbon atom. A triple bond connects the carbons, with one hydrogen linked to each carbon. As a result, each carbon in the alkyne has three carbon bonds and one hydrogen bond, for a total of four valencies.

Valency of Carbon and Its Compounds - Alkene

Alkenes are unsaturated hydrocarbons with the chemical formula CnH2n and double carbon bonds. This and cycloalkanes have the same molecular formula. Alkenes are named similarly to alkanes, with the exception that the suffix is now -ene. Each carbon is double bonded, with two hydrogens bound to it. As a result, each carbon in the alkyne has two carbon bonds and two hydrogen bonds, giving it a total valency of four.

Tetravalence of Carbon

Carbon's ground state electronic configuration is 1s2, 2s2, 2p2. Because it has four valence electrons, the possibility of four bonds forming is greatest. The bonds formed by s orbital electrons will be different from those formed by p orbital electrons. So, in the formation of one molecule of CH4, one C atom will be combined with four H atoms.

C(s)-H(s), C(s)-H(s), C(p)-H(s), and C(p)-H(s) bonds can all be formed (s). We have two 'directional' C (p)-H(s) bonds and two non-directional C(s)-H(s) bonds (s). (Note: S orbitals are spherical and have no specific direction, whereas p orbitals have shapes in three directions: x, y, and z-axis.) The bond strength will also differ because the C (p)-H(s) bond is weaker than the C(s)-H(s) bond because s overlapping is stronger.

However, nearly all of the CH4 bonds are identical. This causes an issue. Hybridization theory has been proposed as a solution to this problem. It is primarily a concept in which atomic orbitals are combined with new hybrid orbitals that are best suited for electron pairing to form chemical bonds.

Three p and one s-orbital are hybridised in fig to produce four identical sp3 hybridised orbitals. Similarly, sp and sp2 hybridization can occur. The only difference will be that sp2 will only have two p orbitals. According to the VSEPR theory, sp and sp2 hybridised molecules have a planar structure. In contrast, sp3 hybridised molecules adopt a tetrahedral shape to become more stable (this structure leads to a minimum energy state).

Valency Chart

The valency chart of the first 30 elements of the periodic table is given below in the table along with these elements' atomic number: