Difference Between Saturated and Unsaturated Bonds

The key difference between saturated and unsaturated bonds is that a saturated bond has no pi bonds whereas unsaturated bonds always have pi bonds.

Chemical bonds are the linkages between atoms. These bonds cause the formation of molecules. There are two major types of bonds; they are the covalent bonds and ionic bonds. However, the bonds in metals are metallic bonds. Covalent bonds form when two atoms share their valence electrons. These covalent bonds can be either saturated or unsaturated depending on the number and type of bond existing between two atoms.

CONTENTS

1. Overview and Key Difference
2. What are Saturated Bonds
3. What are Unsaturated Bonds
4. Side by Side Comparison – Saturated vs Unsaturated Bonds in Tabular Form
5. Summary

What are Saturated Bonds?

Saturated bonds are single bonds. These are covalent chemical bonds. There, two atoms bind with each other via a sigma bond, and thus, there are no pi bonds — the bond forms involving two electrons; one electron from each of the two atoms which form this bond. These electrons are the valence electrons of the atoms. The bond strength of this type of bond is comparatively weak. The two shared electrons exist in between the atoms, and the more electronegative atom will attract the electrons towards itself.

Moreover, this type of bond has the ability to undergo rotations. There, this bond acts as the axis of rotation. A saturated bond forms when following orbitals overlap with each other.

• Two s orbitals
• Two p_z orbitals
• S and p_z orbital
• Two d_z² orbitals
• Linear overlapping of hybrid orbitals.

What are Unsaturated Bonds?

Unsaturated bonds are double bonds and triple bonds between two atoms. These are covalent bonds. Therefore, electrons are shared between atoms. Moreover, there are sigma bonds and pi bonds as well. In a double bond, there is a sigma bond and a pi bond between two atoms. In a triple bond, there is a sigma bond and two pi bonds. A sigma bond forms due to linear overlapping of atomic orbitals while the pi bonds form due to parallel overlapping.

Also, a double bond has four bonding electron between atoms while the triple bond has six electrons there. Because of this large number of electrons between atoms in unsaturated binds, these bonds tend to be more reactive. Moreover, these bonds are stronger and shorter compared to single bonds.

What is the Difference Between Saturated and Unsaturated Bonds?

Saturated bonds are single bonds, and unsaturated bonds are double bonds and triple bonds between two atoms. The key difference between saturated and unsaturated bonds is that a saturated bond has no pi bonds whereas unsaturated bonds always have pi bonds. A further difference between saturated and unsaturated bonds is that there is one electron pair between two atoms in a saturated bond while there are two or three electron pairs between atoms in unsaturated bonds.

Furthermore, an important difference between saturated and unsaturated bonds is that the saturated bonds are comparatively weak, long, and less reactive whereas, the unsaturated bonds are strong, short, and more reactive. Moreover, saturated bonds can undergo rotations while unsaturated bonds cannot.

The below infographic is a comparison summary on difference between saturated and unsaturated bonds.

Summary – Saturated vs Unsaturated Bonds

In summary, saturated bonds are single covalent bonds while unsaturated bonds are double and triple bonds. Therefore, the key difference between saturated and unsaturated bonds is that a saturated bond has no pi bonds whereas unsaturated bonds always have pi bonds.

Reference:

1. Helmenstine, Anne Marie, Ph.D. “Double Bond Definition and Examples in Chemistry.” ThoughtCo, Sep. 8, 2017. Available here 
2. Britannica, The Editors of Encyclopaedia. “Triple Bond.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 14 Apr. 2011. Available here 

Image Courtesy:

1.”Methane-2D-square” (Public Domain) via Commons Wikimedia  
2.”Double-bond”By Fred the Oysteri (CC BY-SA 4.0) via Commons Wikimedia