# What are sp, sp2, sp3 orbitals?

Jul 7, 2018

They are hybridized atomic orbitals formed by mixing s and p orbitals, to describe bonding in molecules.

#### Explanation:

In an $s {p}^{3}$ hybridization, $\textcolor{red}{\text{one}}$ $s$ orbital is mixed with $\textcolor{red}{\text{three}}$ $p$ orbitals to form $\textcolor{red}{\text{four}}$ $s {p}^{3}$ hybridized orbitals. Each of these hybridized orbitals have 25% s character and 75% p character (calculated according to the proportion of s:p mixing). These $s {p}^{3}$ hybridized orbitals are oriented with bond angle of 109.5 degrees to minimize electron repulsion, in a tetrahedral geometry. An example of $s {p}^{3}$ hybridization can be seen in the carbons in ethane.

In an $s {p}^{2}$ hybridization, $\textcolor{red}{\text{one}}$ $s$ orbital is mixed with $\textcolor{red}{\text{two}}$ $p$ orbitals to form $\textcolor{red}{\text{three}}$ $s {p}^{2}$ hybridized orbitals. Each of these hybridized orbitals have 33% s character and 67% p character. These $s {p}^{2}$ hybridized orbitals are oriented with bond angle of 120 degrees, in a trigonal planar (triangular) geometry. The remaining p orbital is unchanged and perpendicular to the plane of the hybridized orbitals. An example of $s {p}^{2}$ hybridization can be seen in the carbons in ethene.

In an $s p$ hybridization, $\textcolor{red}{\text{one}}$ $s$ orbital is mixed with $\textcolor{red}{\text{one}}$ $p$ orbitals to form $\textcolor{red}{\text{two}}$ $s p$ hybridized orbitals. Each of these hybridized orbitals have 50% s character and 50% p character. These $s p$ hybridized orbitals are oriented with bond angle of 180 degrees, in a linear geometry. The remaining two p orbitals are unchanged, and perpendicular to each other and the plane of the hybridized orbitals. An example of $s p$ hybridization can be seen in the carbons in ethyne.

The mixing of orbitals can be seen here:

Orientation of the hybridized orbitals in respective geometries: