Difference Between Atom and Isotope (With Table)

Everything in the world is made of something, from an apple to a human being. If we cut and cut anything to n number of times, we will reach a place where it can’t be separated any further. This matter, which is the smallest unit in the world, is called an Atom. Isotope is a type of Atom which have a different number of neutrons.

They are the fundamental building blocks of chemistry and, in general, of everything. “Element” in general is a term that is used to describe a matter that cannot be broken down any further.

Atom vs Isotope

The difference between an Atom and Isotope is that Isotope is a term that comes in the element of an Atom. In contrast to that, Atoms of the same element with different mass numbers are called Isotopes.

Atoms are the smallest unit of any matter. Every matter starting from solid to liquid to gas, it’s made of something, and that is called Atom. The periodic table, which has 118 elements, shows different types of Atoms. An individual Atom can have an either equal or varied number of protons and neutrons in their nucleus surrounding them.

Isotopes are Atoms, only with different atomic masses which have the same atomic numbers. They are the same as Atoms with a different number of neutrons. Carbon-12, Carbon-13, and Carbon-14 are some familiar examples of Isotopes. Some of the Isotopes can be highly radioactive if they have a high amount of neutrons. They are made up of three subatomic particles: Electrons, Neutrons and protons.

Comparison Table Between Atom and Isotope

Parameters of ComparisonAtomIsotope
Other nameFragment, MoleculeVariant
Year of discovery450 BC1913
Discovered byDemocritus in 450 B.C and John Dalton in 1800Frederick Soddy
 Used forCan be combined to create materials like crystalOil and gas exploration, nuclear medicine
 Name came fromGreek word AromosGreek word Isos and Topos

What is Atom?

The word Atom came from the Greek word ‘Aromos” which translates into “Atoms”, the term was coined by the Greek philosopher Democritus in 400 BC. The concept was not taken positively as Democritus didn’t actually have any evidence of the claims that he was making about Atoms. In 1808, John Dalton wrote and published a 560 pages book, “A new system of Chemical philosophy”, which inscribed about his brief discovery about Atom. There were even some drawings and illustrations of what he thought what an Atom looked like.

An atom is a dense nucleus made up of protons and neutral neutrons. The nucleus is surrounded by electrons that are negatively charged. Since the positive charges get equal to negative charges, thus the Atom has no charge. It is neutral electrically. 

The general structure of an Atom includes:

1. A nucleus is in the centre of the atom.

2. The nucleus includes positively charged protons.

3. And lastly, the nucleus is also made up of neutrons which are neutral.

The process of electronic tunnelling is used in different microscopes to see Atoms. The machine was built by GERD Binning and Heinrich Rohrer in the 70s.

What is Isotope?

The name came from Greek roots “Isos” and “topos” translating into “the same place”. It was first written by Margaret Todd, who was also a chemist, with suggestions by Fredrick Soddy, who is also credited for the discovery of Isotopes as well. Isotopes are the different form of Atoms of the same chemical element. They have the same number of electrons (which are positively charged) and protons (which are negatively charged.) As a fact, The charge on the proton and electron are exactly the same size but opposite and thus cancel each other out. There are two main types of Isotopes:

  1. Stable Isotopes: Elements with the same number of protons but a different number of neutrons. Some common examples include Carbon (13C/12C) and Nitrogen (15N/14N). To be counted perfectly, there are 254 Stable Isotopes.
  2. Unstable Isotopes: These Isotopes decay over time and form into another different Isotope. Artificial Isotopes are called unstable as they are known to be radioactive. Uranium-238 is a common example of an unstable Isotope. Isotopes are also called “radioisotopes” by scientists.

Simply defined, Isotopes are the Atoms of the same element which have the same number of protons as them but a different number of neutrons. The most common use for Isotopes is for nuclear power generation. Other uses include laboratories, medical centres, some type of food plants, etc.

Main Differences Between Atom and Isotope 

  1. The number of neutrons can change in an Atom, but in an Isotope, the number can’t.
  2. Isotopes have higher or bigger masses compared to Atoms since the number of neutrons is different.
  3. Both Atom and Isotopes have different physical properties.
  4. Atom, in general, is a more intensive topic as Isotopes are just a part of an Atom and hence, Atom is a bigger topic to be studied.
  5. There are more types of Atoms compared to Isotopes which are of only two types; Stable and Unstable, and Isotope itself is a type of Atom while Atoms also include Ions, Antimatter, Radioactive and Stable ones.


Atom and Isotope are elements of the smallest thing in the world. They both belong in the chemistry world and are the root of this field. Whether it be an Atom or an Isotope, they can not be seen with a naked eye as the wavelength of light is just too much bigger. Hence it is kind of hard to imagine that they can not even be seen but really are of such great importance and builder of everything in the universe. Quite deep but true.

Everything in the world is made of a thing, the same thing actually, some elementsWhether it be a newborn baby or a piece of ice, these particular elements are called Atoms and Isotopes.


  1. https://pubs.acs.org/doi/abs/10.1021/ja9031083
  2. https://books.google.co.in/books?hl=en&lr=&id=SakNcRLKB34C&oi=fnd&pg=PA37&dq=atom+and+isotope&ots=jNsUBf-WF8&sig=yk1cVhBS9SwlwGNMFKf1FbRIeO8

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