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What is the Difference Between Hybridized and Unhybridized Orbitals

The key difference between hybridized and unhybridized orbitals is that hybridized orbitals are hybrids or mixes of atomic orbitals, whereas unhybridized orbitals are regular atomic orbitals that are not mixed with other atomic orbitals.

The understanding of hybridized and unhybridized orbitals is very important in studying and predicting chemical structures of chemical compounds. Hybridized orbitals are combinations of unhybridized orbitals.

CONTENTS

1. Overview and Key Difference
2. What is Orbital Hybridization
3. What are Hybridized Orbitals 
4. What are Unhybridized Orbitals 
5. Hybridized vs Unhybridized Orbitals in Tabular Form
6. Summary – Hybridized vs Unhybridized Orbitals

What is Orbital Hybridization?

Orbital hybridization is a very important concept in chemistry. It is the concept of mixing atomic orbitals and forming new hybrid orbitals that are suitable for the pairing of electrons in the formation of chemical bonds according to the valence bond theory. For instance, a carbon atom that can form four single bonds contains four valence shell electrons in four hybrid orbitals that form from the hybridization of one “s” atomic orbital with three p atomic orbitals.

Atomic orbitals are model representations of the behavior of electrons within molecules. A simple hybridization is an approximation that is made based on atomic orbitals that are similar to those obtained for the hydrogen atom. It is the only atom that we can solve the Schrodinger equation. When considering heavy atoms like carbon and nitrogen, the atomic orbitals use 2s and 2p atomic orbitals that are similar to the excited state orbitals for hydrogen.

What are Hybridized Orbitals?

Hybridized orbitals are mixed or combined atomic orbitals involved in chemical bonding. They are mixed hybrid atomic orbitals that are useful in the explanation of molecular geometry and atomic bonding properties. These are symmetrically disposed in space. Typically, hybridized orbitals form from the mixing of atomic orbitals of comparable energies.

Hybrid orbitals can be assumed as mixtures of atomic orbitals. These are superimposed on each other in various proportions. For instance, in methane, there is a carbon-hydrogen bond in which the hybrid orbital of the carbon atom has 25% s character and 75% p character. Therefore, it is described as an sp3 hybrid orbital. There are different types of hybridizations, including sp, sp2, and sp3.

Sp orbitals form from the hybridization of one s and one p atomic orbital. This type of hybridized orbitals can be found in alkynes having triple bonds. This combination results in two sp hybridized orbitals and two remaining p atomic orbitals.

Generally, hybridization is helpful in explaining the molecular shape. This is because the angle between bonds is approximately equal to the angle between hybrid orbitals.

What are Unhybridized Orbitals?

Unhybridized orbitals are regular atomic orbitals that are not mixed with other atomic orbitals. Unhybridized p atomic orbitals are used in the formation of π bonds. Typically, two unhybridized p atomic orbitals coming from different atoms can overlap side to side, resulting in a shared electron pair that occupies the space above and below the line that joins the atoms.

All unhybridized orbitals are in the ground state of the atom. The major use of this type of orbital is the formation of double and triple bonds. For example, in sp3 hybridization, there are 4 sp3 hybridized atomic orbitals and no unhybridized orbitals. Therefore, this type of hybridization in an atom can form 4-sigma bonds. But in sp2 and sp hybridizations, there are one and two unhybridized p orbitals left in the hybridized atom, respectively. These unhybridized p atomic orbitals are involved in the formation of triple and double bonds, respectively.

What is the Difference Between Hybridized and Unhybridized Orbitals?

The key difference between hybridized and unhybridized orbitals is that hybridized orbitals are hybrids or mixes of atomic orbitals, whereas unhybridized orbitals are regular atomic orbitals that are not mixed with other atomic orbitals. While hybridized orbitals form sigma bonds, unhybridized orbitals form pi bonds.

The below infographic presents the differences between hybridized and unhybridized orbitals in tabular form for side-by-side comparison.

Summary – Hybridized vs Unhybridized Orbitals

The key difference between hybridized and unhybridized orbitals is that hybridized orbitals are hybrids or mixes of atomic orbitals, whereas unhybridized orbitals are regular atomic orbitals that are not mixed with other atomic orbitals.

Reference:

1. “Hybrid Orbitals.” Chemistry LibreTexts, Libretexts, 26 Aug. 2022.

Image Courtesy:

1. “Shapes of hybrid orbitals” By Officer781 – Own work (CC BY-SA 4.0) via Commons Wikimedia