Difference Between Oxide and Dioxide

The key difference between oxide and dioxide is that oxide is any compound having one or more oxygen atoms combined with another chemical element, whereas dioxide is an oxide containing two atoms of oxygen in its molecule.

The term oxide is a general term that describes the presence of oxygen atoms in a compound. Here, the oxygen atom(s) exists in combination with another chemical element; mostly metals and nonmetals. According to the number of oxygen atoms in the compound, we can name them as monoxide, dioxide, trioxide, etc. Therefore, dioxide is an oxide containing two oxygen atoms per molecule.

CONTENTS

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

What is Oxide?

Oxide is any compound having one or more oxygen atoms combined with another chemical element. The “oxide” here is the divalent anion (O^2–). Typically, metal oxides contain this dianion in which the oxygen atom is in -2 oxidation state. Except for light inert gases (including helium, neon, argon and krypton), oxygen can form oxides with all other elements.

In the formation of an oxide, metals and nonmetals can show their lowest and highest oxidation states. Some oxides are ionic compounds; alkali metals, alkali earth metals and transition metals form these ionic oxides. Other compounds have a covalent nature; metals with high oxidation states can form covalent oxides. Moreover, nonmetals form covalent oxide compounds.

In the above image, the vanadium metal atom has a valency of 5 (total valency is 10 for two vanadium atoms) thus, five oxygen atoms (with a valency of 2 per each oxygen atom) bonded to them.

Moreover, some organic compounds also react with oxygen (or oxidizing agents) to produce oxides, e.g. amine oxides, phosphine oxides, sulfoxides, etc. Furthermore, the number of oxygen atoms in the compound determines whether it is a monoxide, dioxide or a trioxide.

According to their properties, it is also possible to categorize them as acidic, basic, neutral and amphoteric oxides. Acidic oxide can react with bases and form salts. Ex: sulfur trioxide (SO3). Basic oxides react with acids and form salts. Ex: sodium oxide (Na2O). Neutral shows neither acidic or basic properties; thus they do not form salts upon reacting with acids or bases. Ex: carbon monoxide (CO). Amphoteric oxides have both acidic and basic properties; therefore, they react with both acids and bases to form salts. Ex: zinc oxide (ZnO).

What is Dioxide?

Dioxide is an oxide containing two atoms of oxygen in its molecule. A molecule should contain a chemical element with a valency of 4 in order to form a dioxide. It is because one oxygen atom shows a valency of 2. For example, in carbon dioxide, the valency of carbon is 4.

Some Examples of Dioxides

• Carbon dioxide (CO₂)
• Nitrogen dioxide (NO₂)
• Oxygen (O₂)
• Quartz or silicon dioxide (SiO₂)

What is the Difference Between Oxide and Dioxide?

Dioxide is a type of oxide. The key difference between oxide and dioxide is that oxide is any compound having one or more oxygen atoms combined with another chemical element, whereas dioxide is an oxide containing two atoms of oxygen in its molecule. When considering the valency of oxides, the valency of oxygen is 2, and the valency of other elements can vary; however, for dioxides, the valency of oxygen is 2 and valency of other element is essentially 4. So, we can consider this too as a difference between oxide and dioxide.

Summary – Oxide vs Dioxide

Oxide is a general term we use to name any compound containing oxygen atoms in combination with another element. Moreover, according to the number of oxygen atoms, we can name them as monoxide, dioxide, trioxide, etc. The key difference between oxide and dioxide is that oxide is any compound having one or more oxygen atoms combined with another chemical element, whereas dioxide is an oxide containing two atoms of oxygen in its molecule.

Reference:

1.“Oxide.” Wikipedia, Wikimedia Foundation, 2 June 2019, Available here.

Image Courtesy:

1. “Vanadium(V)oxide” By Kemikungen – Own work (Public Domain) via Commons Wikimedia
2. “Sulfur-dioxide-3D-balls” By Ben Mills – Own work (Public Domain) via Commons Wikimedia