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Covalent bond : Definition, Functions, Types, and FAQs

Jul 7, 2022
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Covalent Bond

Electronic configuration has been a very important topic in Chemistry over the years. It is fundamental to know the bonding characteristics of atoms. What is a covalent bond? How does a covalent bond form? These are all some of the common questions that will arise among Chemistry enthusiasts when they talk about electronic configurations. 

Therefore, we are going to address the same in this article. In addition, we will also discuss the in-depth properties and characteristics along with various related concepts.

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Covalent Bond Definition

When the participating atoms share the electrons equally, a covalent bond is formed. The name of such paired electrons is bonding pair or shared pair. We can call covalent bonds molecular bonds. While sharing the bonding pairs, the atoms are capable of achieving stability in their outermost layers. It seems to be similar to that of noble gases.

What is a Covalent Bond?

The elements that contain higher ionisation energy cannot transfer elements and electrons. It is because those elements have extremely low electron affinity. So, it is physically impossible for them to intake electrons. Moreover, these elements’ atoms will potentially share their electrons with other elements’ atoms.

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It is possible that these atoms can also share their electrons with the same element. Doing so will attain octet configuration for the atoms in their allotted valence shell. It further helps them achieve stability. Therefore, association through electron pair sharing among similar or varied kinds is called Covalent Bond.

Formation of Covalent B

The following is the diagrammatic representation of covalent bond formation:

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formation of covalent

Furthermore, the two ways to achieve a covalent bond are:

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  • Electron-sharing between different types of atoms. Example: formation ofNH3 H2 HCl CO2
  • Electron-sharing between the same kinds of atoms. Example: formation of O2 H2 Cl2

Carbon Atom – Covalent Bonding

According to the carbon’s electron configuration, it requires to lose or gain 4 electrons in order to become stable. It seems to be impossible because:

  • Carbon would require a humongous amount of energy in order for it to remove 4 electrons. So, it cannot lose those electrons to become C4+. Moreover, C4+ would contain only 2 electrons held in place by protons. It makes it unstable.
  • The carbon atom can’t gain 4 electrons to become C4-. It is because holding 10 electrons would be very tough for 6 protons. Hence, it makes the atom unstable.

Therefore, from the above points, it is clear that carbon will not donate or gain electrons to fulfil its closest noble gas configuration. So, to form a covalent bond, it shares an electron.

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Covalent Bond Properties

In case the normal valence of an atom cannot be satisfied while sharing a single pair of an electron, the atoms might share more than one pair of electrons within them. The following are a few properties of a covalent bond:

  • These are considered strong and unbreakable chemical bonds that bind the atoms in place.
  • These will only pair the electrons and do not form new ones.
  • After covalent bonds are formed, it is almost impossible to break them.
  • It usually consists of energy of approximately 80 kilocalories per mole (kcal/mol).
  • The directions of the bonded they are based on specific orientations in accordance with each other.
  • Most compounds with covalent bonds will exhibit comparatively low boiling and melting points.
  • The compounds of covalent bonds are insoluble in water.
  • These compounds do not conduct electricity because there are no free electrons available. 
  • These compounds generally contain lower enthalpies of fusion and vaporisation.

Octet Rule

Most atoms contain less than eight electrons (excluding the noble gases) in their valence shell. These shells present in these atoms do not contain stable configurations. Hence, they have to combine with other atoms or another to obtain stable electron configurations.

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Thus, various elements’ atoms’ tendency to obtain a stable electronic configuration of 8 electrons in their valence shells is generally caused by chemical combination. Moreover, the octet rule is the rule that defines the principle of obtaining 8 electrons in an atom’s valence shell.

Lewis discovered easy-to-understand symbols to denote the electrons in the atom’s outermost shell, aka the valence electrons. They were called the Electron Dot System. Hence, the compound’s structure is called Lewis Dot Structure.

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Given below is the representation of the same:

octet rule

Types of Covalent Bonds

The classification of covalent bonds is done in three ways, depending on the no. of shared electron pairs:

  • Single Covalent Bond
  • Double Covalent Bond
  • Triple Covalent Bond
  1. Single Covalent Bonds

When only one electron pair is shared among two atoms, the bond formed is called a single covalent bond. We can denote it using a single dash ‘-‘. This covalent bond form consists of a lesser density. So, it is relatively weaker compared to a triple or double bond. Single bonds have the most stability.

Single covalent bond examples: HCl molecules contain one hydrogen atom that contains one valence electron and one chlorine atom consisting of seven valence electrons. A single bond is formed in such a case. This bond will be between chlorine and hydrogen, sharing one electron.

Let us see its representation:

Single Covalent Bonds

  1. Double Covalent Bonds

The formation of a double covalent bond takes place when two pairs of electrons are shared among two participating atoms. We can denote the double band using double dashes ‘=’. Double bonds are much stronger than single ones because of their electron content. However, the stability of the double it is twice as less as a single bond. 

Double covalent bond examples: The carbon dioxide molecule consists of six valence electrons in one carbon atom and two oxygen atoms with four valence electrons.

In order to complete the octet rule, the carbon atom has to share its two valence electrons in accordance with two oxygen atoms, as shown in the figure:

Double Covalent Bonds

The picture shows that both the oxygen atoms share their two electrons with the same carbon atom and form a double bond.

  • Oxygen molecule: Every oxygen atom consists of 6 electrons in their valence shell during the generation of the oxygen molecule. Also, each of these atoms needs two more electrons to complete their octet. Hence, the atoms are obliged to share two electrons in order for them to form the oxygen molecule. It tends to form a double bond due to two electron pairs.

Oxygen molecule

  • Ethylene molecule: Every carbon atom in ethylene can share two valence electrons along with two atoms of hydrogen. Furthermore, the remaining two electrons are shared with the other carbon atom. Therefore, a double bond is created between the C atoms. Its representation is provided below:

Ethylene molecule

  1. Triple Covalent Bonds

Whenever three electron pairs are shared among the two atoms (participating atoms), the resultant is the formation of a triple bond. We can denote triple bonds as three dashes ‘’. Triple covalent bonds are the least stable of them all.

Triple covalent bond examples: While forming a molecule of nitrogen, every nitrogen atom containing 5 valence electrons shares 3 electrons to form 3-electron pairs. Therefore, we can see that a triple form is formed in the given figure between the two nitrogen atoms:

Triple Covalent Bonds

Difference between Ionic Bond and Covalent Bond

The following table provides the differentiation between the ionic and covalent bonds:

Ionic bond Covalent bond
Ionic bonds do not have any definite shape They have definite shapes
Ionic bonds are generally formed between a metal and a nonmetal These are commonly formed between two nonmetals that contain similar electronegative configurations
Ionic bonds possess high boiling and melting points These possess low boiling and melting points
Ionic bonds have high polarity and are less flammable Covalent bonds have less polarity and are highly flammable
Ionic bonds have a solid state when they are kept at room temperature While keeping covalent bonds at room temperature, they are in a gaseous or liquid state
Example: sulphuric acid and sodium chloride Example: hydrochloric acid and methane

Conclusion

All in all, it is a very strong bond formed between two similar non-metals. From this blog, we have understood the covalent bond definition, how does a covalent bond forms, and saw what examples are, the properties of covalent bonds and the types of covalent bonds.

Furthermore, we have also seen a few differences between covalent and ionic bonds.

Frequently Asked Questions

1.What are nonpolar covalent bonds?

Nonpolar covalent bonds are generally formed whenever there seems to be an equal share of electrons among the atoms. The electronegativity present between two participating atoms is 0. It occurs when the combined atoms have similar electron affinity and diatomic elements. Some examples include the formation of a nonpolar covalent bond, which is found in gas molecules such as nitrogen gas and hydrogen gas.

2.Mention some of the covalent bond examples.

 Some of the real-time examples of covalent bonds include:

  • Ammonia
  • Water
  • Nitrogen gas
  • Chlorine gas
  • Carbon dioxide
  • Oxygen
  • Hydrogen

3.What are the main types of the covalent bond?

 One can classify covalent bonds based on the following three types:

  • Single covalent bond
  • Double covalent bond
  • Triple covalent bond
covalent bond

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