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Molecules vs. Atoms

An atom is the smallest particle of an element that may or may not exists independently; it contains the similar chemical properties as of the element. On the other hand, the molecule is composed of two more atoms held together by the chemical bonding. The molecules can exist in the Free State and can be further divided into the atoms they are made up of. For instance, water molecule comprises of two atoms of Hydrogen, bonded with an atom of Oxygen. The water molecule when gets divided splits into the constituent atoms of Hydrogen and Oxygen.

Key Differences

The atom is the smallest particle of an element that may or may not exists independently. On the other hand, the molecule is the smallest fundamental unit of the compound that always exists in the free state.
Atom comprises of the sub-atomic particles like neutrons, protons, and electrons. Contrary to this, the molecule comprises two or more than two atoms.
The atom is spherical in shape, whereas the molecules exist in the angular, linear or the rectangular shape.
The molecules are formed after the chemical bond holds the atoms. The chemical bond can be of various types, single, double or the triple bond.

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Fundamental unit of the compound.
Smallest particle of an element.


Sub-atomic particles like proton, neutron and electron.


Angular, linear or the rectangular shape.

Molecules and Atoms Definitions


The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms; a group of like or different atoms held together by chemical forces.


A part or particle considered to be an irreducible constituent of a specified system.


A small particle; a tiny bit.


The irreducible, indestructible material unit postulated by ancient atomism.


Plural of molecule


An extremely small part, quantity, or amount.


The smallest unit of an element, having all the characteristics of that element and consisting of a very small and dense central nucleus containing protons and neutrons, surrounded by one or more shells of orbiting electrons. Atoms remain undivided in chemical reactions except for the donation, acceptance, or exchange of valence electrons.


This unit regarded as a source of nuclear energy.


Plural of atom

What are Molecules?

The molecule is the small unit of the matter which always exists in the Free State. It is composed of two or more similar or different atoms. The formation of molecules involves the chemical bonding between them. There are several types of bonding which result in the formation of the molecules; single, double and triple bonds are the types through which the atoms are chemically held together. The molecules can further be divided into the individual atoms. Although the molecules are bigger particles as compared to the atoms, still they can’t be seen through the naked eye. The scientific devices like magnifying microscopes are used to see the molecules. The molecules are not merely the units; they also describe the setting and physical state of the object. The solids, which have absolute shape, are known to have the tightly packed molecules as there is not much space for the molecules to move freely. On the other hand, the liquids have free spaces between the molecules and are less tightly packed, which results in the physical state where the liquids can take the shape of any of the object they are poured in. In the gaseous state, the molecules are free enough to float without colliding with each other. As we know that molecules are the combination of the atoms; the misconception regarding the identical and different atoms combining in is always there. When identical atoms get combined to form the molecules, it is known as the molecule of an element. Contrary to this, when atoms of different elements are combined to form the freely existing molecules, it is termed as the molecule of a compound.

What are Atoms?

Atoms are the smallest particles of the unit that may or may not exist independently; each of the atoms holds the similar properties as of its elements. It can’t be further divided into the subatomic particles. It will be relevant to mention here that atoms are the building blocks of the cells are for the living organisms; everything in this universe is made up of these atoms. The proportion in which the atoms are combined to form the molecules matters a lot like the difference in it can give rise to the different molecules. Just variation in the number of atoms can give rise to whole different molecules. For instance, two atoms of oxygen combine to form the Oxygen molecule, whereas when three atoms of oxygen are combined, it forms Ozone. The atom can’t be seen through the microscope or the naked eyes; it is so small that it can’t be sub-divided into the particles it is comprised up of. The nucleus is the central part of the atom which has the protons and neutrons in the middle of an atom. The protons carry the positive charge, whereas neutrons carry no charge. The electron is the other important particle of the atom which is negatively charged, and it revolves around the nucleus of the atom. The protons and neutrons are made up of the constituents like quarks and gluons, which don’t have much description in the Chemistry.

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