What is the Difference Between Heteroatom and Functional Group

The key difference between heteroatom and functional group is that a heteroatom is any atom other than carbon and hydrogen, whereas functional group is an atom or a group of atoms that is responsible for the chemical reactivity of an organic compound.

The terms heteroatom and functional group are mainly used in organic chemistry because they are important in expressing the properties of organic compounds.

CONTENTS

1. Overview and Key Difference
2. What is a Heteroatom 
3. What is a Functional Group 
4. Heteroatom vs Functional Group in Tabular Form
5. Summary – Heteroatom vs Functional Group 

What is a Heteroatom?

A heteroatom in chemistry is any atom other than carbon and hydrogen. In other words, heteroatoms are atoms that are not carbon or hydrogen. The prefix “hetero-“ refers to the meaning “different” in Greek.

Practically, we use this term to specifically indicate the non-carbon atoms which have replaced carbon atoms in the backbone of molecular structures. The most commonly found heteroatoms in organic compounds include nitrogen, oxygen, sulfur, phosphorous, chlorine, bromine, and iodine. There can also be some metallic atoms such as lithium and magnesium.

Figure 01 : An Organic Compound Having Nitrogen as a Heteroatom

We can use the term heteroatom to describe a protein structure, whereas a heteroatom record is an atom that belongs to a small molecule cofactor that is not a part of a biopolymer chain.

When considering zeolites, the term heteroatom refers to the partial isomorphous substitution of typical framework atoms including silicon, aluminum and phosphorus by other atoms like beryllium, vanadium and chromium.

What is a Functional Group?

Functional groups are specific substituents that occur within a molecule and are responsible for the characteristic chemical reactions those molecules undergo. For example, if the functional group is the same for two molecules that have different chemical structures, the two molecules will undergo similar types of reactions, no matter the size of the molecules. Generally, functional groups are very important in different aspects; in identifying unknown molecules, in determining end products of reactions, in chemical synthesis reactions for the designing and synthesis of new compounds, etc.

Normally, functional groups are attached to a molecule via covalent chemical bonds. In polymers, functional groups are attached to the nonpolar core of carbon atoms, giving the polymer its specific characteristic features. However, functional groups are sometimes charged chemical species. i.e. carboxylate ion group. This makes the molecule a polyatomic ion. In addition, functional groups that attach to a central metal atom in coordinate complexes are called ligands. Some common examples for functional groups include hydroxyl groups, carbonyl groups, aldehyde groups, ketone groups,  and carboxyl groups.

What is the Difference Between Heteroatom and Functional Group?

The terms heteroatom and functional group are useful mainly in organic chemistry because these terms are important in expressing the properties of organic compounds. The key difference between heteroatom and functional group is that a heteroatom is any atom other than carbon and hydrogen, whereas a functional group is an atom or a group of atoms that is responsible for the chemical reactivity of an organic compound. Moreover, nitrogen atoms in the pyridine molecule are examples of heteroatoms whereas aldehydes, ketones, alcohols, amides, carboxylic acids, etc. are examples of functional groups.

The below infographic lists the differences between heteroatom and functional group in tabular form for side by side comparison.

Summary – Heteroatom vs Functional Group

Heteroatom and functional groups can be found in organic compounds. The key difference between heteroatom and functional group is that a heteroatom is any atom other than carbon and hydrogen, whereas a functional group is an atom or a group of atoms that is responsible for the chemical reactivity of an organic compound.

Reference:

1. “Heteroatom.” Chemistry LibreTexts, Libretexts, 24 Aug. 2020.

Image Courtesy:

1. “Pyridine” By Calvero. – Selfmade with ChemDraw. (Public Domain) via Commons Wikimedia

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