Types of Covalent Bonds

In order for a covalent bond to form, electrons from both participating atoms must be shared equally between them. A shared pair or bonding pair is the name given to the pair of electrons that are involved in this type of bonding. Covalent bonds are referred to as molecule bonds in some circles. In a similar way to noble gas atoms, the sharing of bonding pairs will ensure that the atoms achieve stability in their outer shell by sharing bonding pairs.

The Characteristics of a Covalent Bond

If sharing a single electron pair between atoms does not allow the atoms to maintain their normal valence, the atoms may choose to share more than one electron pair between themselves. The following are the characteristics of covalent bonds:

• The formation of new electrons does not occur as a result of covalent bonding between two atoms. The bond is merely a means of connecting them.

• They are chemical bonds that exist between atoms that are extremely strong in nature.

• Covalent bonds are extremely difficult to break on their own after they have been formed.

• Unlike covalent bonds, which are directional in nature, covalent bonds are directional in the sense that the atoms that are bonded have distinct orientations relative to one another.

• The melting and boiling points of the majority of covalently bound compounds are relatively low.

• Compounds with covalent bonds typically have lower vaporisation and fusion enthalpies than other types of compounds.

• Compounds formed through covalent bonding do not conduct electricity due to the absence of free electrons in the compound.

• Covalent compounds are not soluble in water and must be dissolved in acid.

Different Types of Covalent Bonds

The covalent bond can be classified into three types: Single Covalent Bond, Double Covalent Bond, and Triple Covalent Bond, depending on the number of electron pairs that are shared.

Single bond

One bond is formed when only one pair of electrons is shared by the two atoms that are participating in the bonding process. Using a single dash, it can be distinguished from other words (-). Because of its lower density and weaker strength than double or triple bonds, this type of covalent bond is the most stable type of bond available.

Example: A molecule of hydrochloric acid (HCl) consists of one Hydrogen atom with one valence electron and one Chlorine atom with seven valence electrons. Because they are both sharing an electron, hydrogen and chlorine form a single bond in this case.

Double Bonds

A double bond is formed when two pairs of electrons are shared by two participating atoms and are held together by their shared electrons. It is denoted by two dashes (=) in the text. Double covalent bonds are significantly stronger than single covalent bonds, but they are also significantly less stable.

When one carbon atom has six valence electrons and two oxygen atoms each have four valence electrons, for example, the result is a carbon dioxide molecule. Carbon shares two of its valence electrons with one oxygen atom and two more with another oxygen atom to complete its octet of valence electrons with the other oxygen atom. CO2 contains two double bonds due to the fact that each oxygen atom shares two electrons with each carbon atom.

Oxygen Molecule: Each oxygen atom in the formation of the oxygen molecule has six electrons in its valence shell, which is the shell in which the electrons are arranged. Each atom requires two additional electrons in order to complete their octet. Therefore, two electrons are shared by the atoms, resulting in the formation of an oxygen molecule. Because the two oxygen atoms share two electron pairs, they are able to form a double bond.

Triple Bond

It is possible to form a triple bond when two participating atoms share three pairs of electrons between them. Triple covalent bonds are the least stable type of covalent bond, and they are denoted by three dashes on the atomic diagram.

The formation of a molecule such as that of nitrogen requires the contribution of three electrons from each nitrogen atom with five valence electrons, which in turn results in the formation of three electron pairs that can be shared. An unusual triple bond is formed as a result of this reaction between the two nitrogen atoms.

Polar Covalent Bonds

It is possible to form this type of covalent bond when the electronegativity of the combining atoms is different, resulting in unequal electron sharing. Electrons will gravitate toward atoms that are more electronegative. The electronegative difference between the atoms is greater than zero but less than two.

As a result, the electron pair that is shared with that atom will be closer to that atom. Consider the case of molecules that form hydrogen bonds as a result of an unbalanced electrostatic potential, as an illustration. In this instance, the hydrogen atom interacts with the electronegative elements fluorine, hydrogen, and oxygen.

Nonpolar Covalent Bond

When two atoms share an equal number of electrons, this type of covalent bond is formed between them. The difference between the electronegativity of two atoms is equal to zero.

It occurs whenever the atoms that are combining have electron affinities that are similar. Examples of nonpolar Covalent Bonds include those found in gas molecules such as hydrogen gas, nitrogen gas, and other similar gases.

Coordinated or Dative Covalent Bond

It is possible to form a coordinated or Dative Covalent Bond when one of the atoms in the bond provides electron sharing by way of another of the atoms in the bond. The reaction between ammonia and boron trifluoride is responsible for this. Nitrogen has two free electrons, whereas boron does not have any electrons available. By combining nitrogen and boron, they are able to complete their final shell with eight electrons.

Conclusion

A shared pair or bonding pair is the name given to the pair of electrons that are involved in this type of bonding. Covalent bonds are referred to as molecule bonds in some circles.If sharing a single electron pair between atoms does not allow the atoms to maintain their normal valence, the atoms may choose to share more than one electron pair between themselves. The covalent bond can be classified into three types: Single Covalent Bond, Double Covalent Bond, and Triple Covalent Bond, depending on the number of electron pairs that are shared. When two atoms share an equal number of electrons, this type of covalent bond is formed between them. The difference between the electronegativity of two atoms is equal to zero.