Difference Between sp sp2 and sp3

The key difference between sp sp2 and sp3 is that the sp hybrid orbitals have 50% s orbital characteristics and sp2 hybrid orbitals have 33% s orbital characteristics whereas sp3 hybrid orbitals have 25 % s orbital characteristics.

The terms sp, sp2 and sp3, refer to different hybridizations of orbitals that leads to form hybrid orbitals. Orbitals are hypothetical regions around a nucleus of an atom, which contain electrons of that atom. These orbitals can undergo hybridization in order to form new hybrid orbitals that can form covalent chemical bonds. There are several forms of hybridizations according to the atomic orbitals that take part in the hybridization process. Sp, sp2 and sp3 are some common hybridizations that involve in the s and p orbitals of an atom.

CONTENTS

1. Overview and Key Difference
2. What is sp
3. What is sp2
4. What is sp3
5. Side by Side Comparison – sp vs sp2 vs sp3 in Tabular Form
6. Summary

What is sp?

Sp hybridization is the simplest form of hybridization in which an s orbital overlaps with a p orbital to form two new sp orbitals. An electron shell contains three p orbitals. In this hybridization, one of these three p orbitals mixes with an s orbital of the same atom. Therefore, there are two un-hybridized p orbitals remaining in these atoms.

The ratio of mixing of the two atomic orbitals is 1:1 (s:p). Hence the new hybrid orbital has 50% of s orbital characteristics and 50% of p orbital characteristics. This mixing of the s and p atomic orbitals form two new hybrid orbitals. These two orbitals arrange in a linear spatial arrangement; directing each atomic orbital to the opposite directions. This arrangement results in the least strain between the two orbitals. Hence, the bond angle will be 180◦.

What is sp2?

Sp2 hybridization is a form of orbital hybridization in which one s orbital overlaps with two p orbitals to form three new hybrid orbitals. Since there are three p atomic orbitals in an atom, this hybridization leaves one un-hybridized p orbital. Unlike in sp hybridization, in this form of hybridization, the s characteristic of each sp2 hybrid orbital is 33% present while the p orbital characteristic is 66%.

However, these are only approximate values because the ratio between the three atomic orbitals involves in this hybridization is s:p = 1:2.

Then the s characteristic equals 100/3 = 33.33%

And the p characteristic equals (100/3) x 2 = 66.66%

These three new hybrid orbitals get the trigonal planar spatial arrangement in order to minimize the strain between the orbitals. Also, the bond angle between these orbitals is 120◦.

What is sp3?

Sp3 hybridization is a form of orbital hybridization in which one s orbital overlaps with three p orbitals. Therefore, there are no un-hybridized p orbitals since all the p orbitals involve in the hybridization process.

Hence, this results in 4 new hybrid orbitals. Since the ratio between s and p orbitals is 1:3, the s characteristic of each hybrid orbital is 25% while the p orbital characteristic is 75%. These new hybrid orbitals arrange in a tetrahedral arrangement with 109.5◦ bond angle.

What is the Difference Between sp sp2 and sp3?

Sp hybridization is the simplest form of hybridization in which an s orbital overlaps with a p orbital to form two new sp orbitals, and an Sp2 hybridization is a form of orbital hybridization in which one s orbital overlaps with two p orbitals to form three new hybrid orbitals whereas Sp3 hybridization is a form of orbital hybridization in which one s orbital overlaps with three p orbitals. This is the fundamental difference between sp sp2 and sp3 hybrid orbitals. Moreover, each of the new hybrid orbitals that form in these three forms of hybridizations has different s orbital characteristics because the s orbitals mix with different numbers of p orbitals. Therefore they have different p orbital characteristics as well.

However, we can emphasize the major difference between sp sp2 and sp3 hybridization according to the s characteristic of these hybrid orbitals; sp hybrid orbitals have 50% s orbital characteristics, and sp2 hybrid orbitals have 33% s orbital characteristics whereas sp3 hybrid orbitals have 25 % s orbital characteristics. Moreover, each hybridization leaves different numbers of un-hybridized orbitals. For example, the sp hybridization involves only 1 p atomic orbitals. Thus, it leaves two un-hybridized p atomic orbitals.

The below infographic shows a detailed side by side comparison on the difference between sp sp2 and sp3 hybridization.

Summary – sp sp2 vs sp3

Hybridization is a process in which atomic orbitals mix with each other to form new hybrid orbitals that can undergo covalent chemical bonding. The simplest forms of atomic orbital hybridizations are sp, sp2 and sp3 hybridizations. The key difference between sp sp2 and sp3 is that the sp hybrid orbitals have 50% s orbital characteristics and the sp2 hybrid orbitals have 33% s orbital characteristics whereas the sp3 hybrid orbitals have 25 % s orbital characteristics.

Reference:

1. “Orbital Hybridisation.” Wikipedia, Wikimedia Foundation, 13 Sept. 2018. Available here  
2. Libretexts. “Hybridization.” Chemistry LibreTexts, Libretexts, 21 July 2016. Available here 

Image Courtesy:

1.”AE2h”By Jfmelero – Own work, (CC BY-SA 3.0) via Commons Wikimedia 
2.”AE3h”By Jfmelero – Own work, (CC BY-SA 3.0) via Commons Wikimedia  
3.”AE4h”By Jfmelero – Own work, (CC BY-SA 3.0) via Commons Wikimedia