Concept of Covalent Bond

The interatomic coupling that emerges from the sharing of such an electron pair across two atoms is known as a covalent bond in chemistry. The electrical interaction of their nuclei for the identical electrons causes the binding.

Covalent Bonding could be Achieved in two Ways:

• Electron sharing amongst atoms with the same type For example, the formation of H2, Cl2, O2, and other gases.

• Electron sharing across different types of atoms For example, the formation of CH4, H2O, and NH3.

Properties of Covalent Compounds

• The melting and boiling points of most covalent compounds are relatively low.

While the ions in such an ionic compound are strongly connected to one another, covalent bonds allow molecules to split when a lower amount of energy is applied. As a result, the melting and boiling temperatures of molecular compounds are often low.

Covalent chemicals have lower fusion and vaporisation enthalpies than ionic molecules.

The temperature of fusion is the amount of oxygen needed to melt one mole of a solid substance under constant pressure. The enthalpy of vaporisation is the amount of energy required to evaporate one mole of a liquid at constant pressure.

• Covalent substances are typically soft and malleable.

This is due to the fact that covalent bonds are flexible and easy to break. Molecular compounds take the shape of gases, liquids, and soft solids due to their covalent bonding. 

• Many covalent compounds are difficult to dissolve in water.

Many exceptions to this rule exist, just as many salts (ionic substances) do not dissolve easily in water. Many covalent compounds, on the other hand, are polar molecules that dissolve readily in a polar solvent like water.

Types of Covalent Bonds

The amount of shared electron pairs in a covalent connection can be categorised into three types. 

• Single Covalent Bond
• Double Covalent Bond
• Triple Covalent Bond

Single Covalent Bond

Single covalent bonds are those in which only one pair of electrons is shared between both the two participating atoms. One dash is used to represent it (-). Although it is the most durable link, this type of covalent bond has a lower density and is weaker than double and triple bonds.

Example: One Hydrogen atom has one valence electron, while one Chlorine atom has seven valence electrons in the HCl molecule. By sharing one electron, a single bond is established between hydrogen and chlorine, completing the octet of one molecule of HCl.

Double Bonds

A double bond is established when two shared between two atoms are shared between the two respective atoms. It is indicated by two dashes (=). Although doubled covalent bonds are more potent than single covalent connections, they are even less stable.

Example One carbon atom has six valence electrons and oxygen atoms of oxygen have four valence electrons in a carbon dioxide molecule.

Triple Bond

A triple bond is established when the two involved atoms share three pairs of electrons. Three dashes (≡) are used to denote triple covalent bonds. These are the covalent bonds that are the least stable.

Example: Each nitrogen atom with five valence electrons donates three electrons to each other to complete the octet in the creation of a nitrogen molecule. As a result, between both the two nitrogen atoms, a triple bond is created.

We have several types of bonds: polar, nonpolar, and coordinated, depending on each atom’s affinity for electrons.

Nonpolar Covalent Bond

This bond is formed between atoms that have the same electronegativity. Between atoms with such a higher electronegativity of less than 0.4, this form of link can also be maintained.

Example: Two chlorine atoms with about the same electronegativity share an electron pair in a nonpolar covalent connection to form the chlorine molecule Cl2

Polar Covalent Bond

A polar covalent link is created when two non-metallic atoms with electronegativity differences of 0.4 to 1.7 form a covalent connection. When these two atoms collide, the shared electrons gravitate toward the more electronegative atom.

Example: The oxygen and hydrogen atoms in the water molecule form two polar covalent connections.

The hydrogens’ electrons stay closer and stronger around the more electronegative oxygen in the water molecule H2O.

Fluorine F possesses seven valence electrons and is the most electronegative element (4.0). By forming a polar covalent bond with hydrogen, hydrogen fluoride (HF) is generated.

Coordinated or Dative Covalent Bond

• Whenever one of the atoms in the relationship is the one who gives the electrons to share, this type of bond is formed. This is accomplished by combining NH3 ammonia and boron trifluoride BF3 in a reaction

Conclusion:

When atoms share the electron pairs, this is known as covalent bonding. In order to obtain additional stability, atoms will covalently link with neighbouring atoms in order to build a full electron shell. By exchanging their outermost (valence) electrons, atoms can fill out their outer electron shell and boost stability. In order to gain stability, nonmetals will quickly make covalent bonds with certain other nonmetals, and depending on how many electron densities they have, they can build one to triple covalent bonds with some other nonmetals. Although it is often understood that when atoms form covalent connections, they share electrons, this is not always the case.