Difference Between Catenation and Allotropy

The key difference between catenation and allotropy is that catenation refers to the biding of an element to itself, forming chain or ring structures, whereas allotropy refers to the existence of different physical forms of the same chemical element.

Although both catenation and allotropy express a similar idea about the different arrangements of atoms of the same chemical element, they are different terms that describe different states of matter.

CONTENTS

1. Overview and Key Difference
2. What is Catenation 
3. What is Allotropy
4. Side by Side Comparison – Catenation and Allotropy in Tabular Form
5. Summary

What is Catenation

In inorganic chemistry, catenation is the ability of atoms of a particular chemical element to bind with each other, forming a chain or ring structure. Generally, the chemical element carbon is involved in catenation because carbon is able to form aliphatic and aromatic structures via binding a large number of carbon atoms. Moreover, there are some other chemical elements that can form these structures, such as sulfur and phosphorous.

When a certain chemical element undergoes catenation, the atoms of that element must have a valency that is at least two. Furthermore, this chemical element must be able to form strong chemical bonds between the atoms of its kind; e.g. covalent bonds. We can also name polymerization as a type of catenation reaction. Examples of chemical elements that can undergo catenation include carbon, sulfur, silicon, germanium, nitrogen, selenium and tellurium.

What is Allotropy?

In inorganic chemistry, allotropy is the existence of two or more different physical forms of a chemical element. These different physical forms exist in the same physical state, mostly in the solid-state. Therefore, we can say that these are different structural modifications of the same chemical element. Further, allotropes contain atoms of the same chemical element that binds with each other in different ways.

However, these different forms may have different physical properties because they have different structures and chemical behaviours. One allotrope is able to convert into another when we change some physical factors such as pressure, light, temperature, etc. Therefore these physical factors affect the stability of these compounds. Some examples of allotropes include the followings:

1. Allotropes of carbon – diamond, graphite, fullerenes, etc.
2. Allotropes of phosphorous – white phosphorous, red phosphorous, etc.
3. Allotropes of oxygen – dioxygen, ozone, etc.
4. Allotropes of arsenic – yellow arsenic, gray arsenic, etc.

What is the Difference Between Catenation and Allotropy?

Catenation and allotropy are different from each other according to the arrangement of atoms. Catenation is the ability of atoms of a particular chemical element to bind with each other, forming a chain or ring structure. Allotropy in inorganic chemistry is the existence of two or more different physical forms of a chemical element. Thus, the key difference between catenation and allotropy is that catenation is the biding of an element to itself, forming chain or ring structures, whereas allotropy is the existence of different physical forms of the same chemical element.

The following table summarizes the difference between catenation and allotropy.

Summary – Catenation vs Allotropy

Catenation and allotropy are important chemical terms. The key difference between catenation and allotropy is that catenation refers to the biding of an element to itself forming a chain or ring structure whereas allotropy refers to the existence of different physical forms of the same chemical element.

Reference:

1. Helmenstine, Anne Marie. “Catenation Definition and Examples.” ThoughtCo, Feb. 11, 2020, Available here.

Image Courtesy:

1. “Alpha-Linolenic acid Structural Formulae V.2” By Jü – Own work (CC0) via Commons Wikimedia
2. “Allotropes Of Carbon” By Diepizza – Own work (CC BY-SA 4.0) via Commons Wikimedia