Covalent Bond
A covalent bond is a type of chemical bond formed between two atoms by the sharing of electrons. In simple terms, a covalent bond is the exchanging of electrons between particles to achieve the honorable gas configuration of individual iotas. In a covalent bond, atoms share one or more pairs of electrons in order to achieve a more stable electron configuration.
Characteristics of Covalent Bond
Key characteristics of covalent bonds are as follows:
- Electron Sharing: Covalent bonds occur between nonmetal atoms or between nonmetal and hydrogen atoms. In this type of bond, each atom contributes one or more electrons to a shared electron pair. The shared electrons are attracted to the nuclei of both atoms, holding them together.
- Electronegativity: In a covalent bond, the electronegativity difference between the two atoms is relatively small (usually less than 1.7 on the Pauling scale). This means that neither atom completely loses or gains electrons, but instead, they share the electrons in a more equal manner.
- Stable Electron Configuration: By sharing electrons, both atoms can achieve a stable electron configuration. They strive to attain a complete outer electron shell with eight valence electrons (except for hydrogen and helium), known as the octet rule. Sharing electrons allows the atoms to fill their valence shells without undergoing a complete electron transfer.
- Molecular Orbitals: In covalent bonding, the shared electrons occupy molecular orbitals that extend over both atoms. These molecular orbitals are formed by the overlapping of atomic orbitals from the participating atoms. The formation of molecular orbitals allows for the delocalization of electrons, resulting in the stability of the molecule.
- Multiple Bonds: In covalent bonding, there can be the formation of single, double, or triple bonds based on the sharing of pair of electrons.
Types of Covalent Bonds
The covalent bond can be categorized into the following categories based on the number of shared electron pairs:
- Single Covalent Bond
- Double Covalent Bond
- Triple Covalent Bond
Let’s understand these types as follows:
Single Bonds
When just one pair of electrons is shared between the two participating atoms, a single bond is established. One dash is used to symbolize it (-). Although it has a lower density and is weaker than double and triple bonds, this type of covalent bond is the most stable.
For Example, One Hydrogen atom has one valence electron and one Chlorine atom has seven valence electrons in the HCL molecule. By sharing one electron, a single bond is established between hydrogen and chlorine in this situation.
Double Bonds
When two pairs of electrons are shared between the two participating atoms, a double bond is established. Two dashes (=) are used to indicate it. Double covalent bonds are substantially more powerful than single covalent bonds, but they are also less stable.
Example: One carbon atom has six valence electrons and two oxygen atoms have four valence electrons in a carbon dioxide molecule.
Carbon shares two of its valence electrons with one oxygen atom and two with another oxygen atom to complete its octet. CO2 has two double bonds because each oxygen atom shares its two electrons with carbon.
Triple Bond
When the two participating atoms share three pairs of electrons, a triple bond is established. The least stable forms of covalent bonds are triple covalent bonds, which are indicated by three dashes (≡).
For Example: Each nitrogen atom with five valence electrons contributes three electrons to form three electron pairs for partaking in the construction of a nitrogen molecule. The two nitrogen atoms create a triple bond as a result.
Based on Polarity, covalent bonds can be classified as follows:
- Polar Covalent Bond
- Nonpolar Covalent Bond
Let’s understand these types of covalent bonds as follows:
Polar Covalent Bond
Because the electronegativity of the combining atoms differs, this sort of covalent bond develops when electrons are shared unequally. The attraction for electrons will be larger for more electronegative atoms. Between the atoms, the electronegative difference is more than zero but less than 2.0. As a result, that atom’s shared pair of electrons will be closer.
Example, An uneven electric potential causes molecules to form hydrogen bonds. The hydrogen atom interacts with the electronegative fluorine, hydrogen, or oxygen in this situation.
Nonpolar Covalent Bond
- When atoms share an equal number of electrons, this sort of covalent connection is produced. The difference in electronegativity between two atoms is zero. It happens when the atoms joining have a comparable electron affinity (diatomic elements).
Example, Gas molecules such as hydrogen and nitrogen include nonpolar covalent bonds.
Polarization of Covalent Bonds
The electron cloud is always closer to the more electronegative of the two atoms participating in the sigma bond in sigma bonds between two distinct atoms. As a result, the bond develops a permanent dipole, and the covalent bond is said to be polarised.
Types of Chemical Bonding
Types of Chemical Bonds as the name suggest explore the different types of chemical bonds which exist and form in the domain of chemistry. Bons such as Ionic, Covalent, Hydrogen, and Metallic include polar and non-polar bonds. Understanding these bonds is necessary as without knowing how these bonds are formed it is very difficult to analyse anything in the chemistry. In this article, we will explore all the different types of chemical bonds, their formation, properties, and examples as well. So, let’s begin our journey of learning about chemical bonds and their various types.