Single Bond, Double Bond and Triple Bond

Covalent bonding is seen when atoms share pairs with electrons. Atoms will covalently bond with other atoms to gain greater stability, which is gained through forming a full shell of electrons. Through exchanging most (valence) electrons out there, atoms will fill up their outer shell of electrons and gain stability.

The octet rule explains that atoms of main-group elements seem to bind, So that all of the atoms have eight electrons in their valence shells, and attain the same noble gas electronic configuration.

In covalent bonds, the atoms tend to share their electrons, so the atoms involved in covalent bonding follow the Octet law and attain the noble gas configuration.

Explaining the formation of covalent bond is explained with an example:

If there are two chlorine atoms, with seven valence electrons each for chlorine. Thus, each of these chlorine atoms only needs one more electron to complete the valency of its outer shell. These atoms bind together by sharing two electrons and forming one bond. 

The negative electrons are driven into each atom's positively charged nucleus, thereby holding the atoms together.

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Bases on the number of pairs of electrons shared between atoms, there are three types of bond. They are:

  • Single bond

  • Double bond

  • Triple bond

What is a Single bond? 

A single bond is formed when one pair of electrons are shared between two atoms. 

This bond type is relatively weak and has a smaller electron density than a double bond and a triple bond, but is the most stable because it has a lower reactivity level. It means that the loss of electrons to atoms is less susceptible.

Single bond symbol: A single line represents a bond between two atoms (i.e., involving one electron pair)

Single bond example: Cl2, HCl, NH3 etc.

What Is A Double Bond?

A Double bond is formed by the two atoms sharing two pairs of electrons

This type of bond is stronger than a single bond but less stable because of its greater reactivity than a single bond.

Double bond symbol: double lines (=) represents a double bond between two atoms (i.e., involving two electron pairs)

Double bond example:  O2, CO2 etc.

What Is A Triple Bond?

A Triple Bond is formed when a molecule shares three pairs of electrons between two atoms. It is the least stable of the three general types of covalent bonds, because losing an electron is very vulnerable.

Triple bond symbols: triple lines (≡) indicates a triple bond

Triple bond example: N2, C2Hetc

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Key Points:

When pairs of electrons are shared between the atoms it results in the formation of covalent bonds. The octet rule explains that atoms of main-group elements seem to bind So that all of the atoms have eight electrons in their valence shells, and attain the same noble gas electronic configuration. If one pair of electrons are shared between atoms, then a single bond is formed.it is represented by a single line. If two pairs of electrons are shared between atoms, then the double bond is formed and represented by two parallel lines. When three pairs of electrons are shared between two atoms then a triple bond is formed.

FAQ (Frequently Asked Questions)

1. Which bond is more stable?

Stability of single double and triple bonds is explained below:

In covalent bond, a greater number of electrons are shared among atoms, then the stronger the bond exists.

In single bond, 2 electrons are shared, in double bond four electrons are shared and in triple bond six electrons are shared. Thus, triple bond is difficult to break since it is the strongest bond.

Between the two atoms, stronger the bond, more stable the molecule. Thus, triple bond is more stable.

2. Explain the formation of triple bond?

On the periodic table, nitrogen is a diatomic molecule belongs to the VA family. Nitrogen has five valence electrons, so three more valence electrons are required to complete its octet.

By sharing three electrons with another nitrogen atom, a nitrogen atom can fill its octet, forming three covalent bonds, the so-called triple bond.

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3. Is double bond longer than a single bond?

The disparity in distance between the nuclei of the bonded atoms is another result of the presence of multiple bonds between the atoms. Double bonds are smaller than single bonds, and triple bonds are smaller than double bonds.