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Molecules of Elements

Molecules: An Introduction

Last updated date: 25th Mar 2023
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All living things in this world are made up of Atoms. An atom is nothing but the smallest unit that forms a chemical element. Every other thing that is solid, liquid, and gas is composed of atoms. Atoms consist of protons, neutrons, and electrons that are present inside the nucleus of an atom. But what happens when two or more atoms meet? They form molecules. Molecules are formed when two or more atoms are joined together by chemical bonds. It is not that easy to understand the properties and structure of both atoms and molecules, but once understood the concept of it, it’s an interesting thing to learn.

Molecule of Element

When two more atoms are joined together by chemical bonds, a molecule is formed. As we may have learned from Dalton's atomic theory, all matter is made up of atoms, whether it can be elements. Elements are nothing but chemical substances composed of the same number of atoms. When two or more elements meet, a compound is formed. To find out the relation between molecules and elements, we need to study further.

What are Molecules of Elements?

Elements are formed when the same types of atoms are formed. The ratio of the number of atoms forming a molecule is the same. The properties of elements are determined by their structure. Elements can be formed by single or more atoms. For instance, we can take oxygen, as oxygen has 2 atoms (O2). Atoms are not drawn to scale. When these elements are joined together, a compound is formed. In this case, we can take H2O. Water has two hydrogens and one oxygen atom. Likewise, larger chemical compounds like methane (CH4). From these, we can learn how a group of atoms with nucleus can form elements and compounds with different properties and structures.

List of Molecule of Element

Elements can be monatomic, diatomic, triatomic, and polyatomic. Monatomic means elements made of one atom, diatomic refers to elements of two atoms, triatomic refers to elements made of three atoms, and polyatomic means elements made of more atoms. Some of the best ways we can learn about the list of elements are by going through the chemical structure of molecules.



Type of Element




Bleach (sodium hypochlorite)


















Example of Molecule

All the elements of the periodic table are molecules. They are differentiated based on the number of atoms combined. Their structure also varies, along with their respective types. For example, when two identical atoms are formed, like O2, they compose homonuclear diatomic molecules (as atoms contain nuclei of positive charge, surrounded by electrons of negative charge).

Likewise, in carbon monoxide molecules (CO2), there are two different atoms and hence they compose heteronuclear diatomic molecules. As atoms consist of a single positively charged nucleus, surrounded by negatively charged electrons, during the chemical bonding, the electrons interact with each other along with the nuclei, causing a surge of energy between them and when this energy is lowered, a molecular compound or element is formed. Molecules do not break easily due to the electron pairs or covalent bonds holding them together.

Difference Between Atoms and Molecules



Atoms are the smallest particle that can exist.

Two or more atoms combined to form molecules.

Atoms may not be stable due to the presence of electrons in the outer shells.

Molecules attain stability.

They contain protons, neutrons, and electrons.

Two or more atoms are formed and hence, they are strong.

Examples: Oxygen (O), phosphorus (p), and sulphur (s) etc.

Examples: Oxygen (O2), water (H2O), and sulphur (S8).

Interesting Facts

  • Atoms are mostly empty space.

  • There are over 100 different kinds of atoms.

  • The same elements occur everywhere in the universe.

  • Astatine is the rarest element on Earth.

Key Features

  • Molecules are formed when two or more atoms are combined together.

  • All matter is made up of atoms, even elements.

  • When two or more elements meet, they form compounds.

  • An atom has a nucleus at the centre and electrons surrounding it.

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FAQs on Molecules of Elements

1. What are the chemical structures of molecules?

The properties of elements and compounds are determined by their structure.    The simplest structural unit of an atom. Atoms are very small. A hundred million (100,000,000) hydrogen atoms put side by side are only as long as one centimetre. Some elements are Monatomic meaning they are made of a single (mon-) atom (atomic) in their molecular form. Helium is an example of a monatomic element. Other elements contain two or more atoms in their molecular form.

2. What are the most common elements?

  • Water: water participates in many biochemical reactions and serves as the building block of most tissues. 

  • Oxygen: Oxygen is a chemical element that occurs in the air as a gas composed of two oxygen atoms (O2).

  • DNA: DNA is the acronym for deoxyribonucleic acid. While water and oxygen are small, DNA is a large molecule or macromolecule.

  • Haemoglobin: Haemoglobin is another super-sized macromolecule that you can't live without. It's large.

  • Cholesterol: Cholesterol gets a bad rap as an artery-clogging molecule, but it's an essential molecule that's used to make hormones.

3. How many molecules are in the cell?

There are 42 million protein molecules in a simple cell, revealed a team of researchers led by grant brown, a biochemistry professor at the University of Toronto's Donnelly Centre for cellular and biomolecular research. Analysing data from almost two dozen large studies of protein abundance in yeast cells, the team was able to produce for the first time reliable estimates for the number of molecules for each protein. Proteins make up our cells and do most of the work in them.