If I ask you what are things made up of? Your answer would probably be atoms, which are like tiny spherical balls. But how well do you know these particles that makes up almost everything?

What is an Atom?What is an Atom

Background – History of Atom

If we look back to the history, the idea of atoms was developed thousands of years earlier than its establishment in modern science. Greek philosopher Leucippus and his pupil Democritus are believed to have developed an idea that everything is made up of similar small indivisible particles during 5th century BCE.

But the quantitative studies of reactions were conducted by John Dalton and atomic theory was hypothesized. Finally, the statistical study of Brownian motion by Albert Einstein, the greatest mind of all time was used by Jean Perrin to experimentally calculate the mass of atoms verifying the atomic theory of matter. And now here we are, dissecting atom and discerning the very fundamental nature of nature.

What is an Atom?

An atom is the most fundamental particle that makes all of the matter that are present in the Universe. The screen you are seeing is made up of atoms, the eyes you are seeing with is made up of atoms and even the brain with which you are thinking and analyzing these sentences is made up of atoms. Not just the things that you can see, but the invisible thing like air is also made up of atoms.

If you wonder what these atoms are? Imagine bricks, they are fundamental building blocks of a building, aren’t they? Every building is made from combination of those bricks, which may come in varieties of sizes or types. Just like bricks that are building blocks of buildings, atoms are building blocks of matter.

Atoms are further made up of particles like protons, neutrons and electrons. Protons are heavy and positively charged, neutrons are heavy but chargeless while electrons are negatively charged and lighter in comparison with protons and neutrons.

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Protons and neutrons are situated at the centre of an atom and make up the nucleus while electrons are revolving around the nucleus like planets revolving around the Sun (not actually so). The nucleus occupy very small volume but accounts for almost all the mass of an atom so that an atom is nearly completely vacant.

On the basis of the number of protons, neutrons and electrons, there can be a lot of varieties of atoms. The number of protons determines a type of element, suppose an atom with one proton is hydrogen and that with six protons is carbon.

The same number of protons but different number of neutrons results same elements and such elements with the difference in the number of neutrons are called isotopes. There are 94 naturally existing elements whereas 24 elements are synthetic. Accounting for all these elemental atoms and their isotopes there are thousands of atoms that exist in the Universe.


Ashwin Khadka is a Physics graduate from Tribhuvan University, Kathmandu, Nepal. He is a science enthusiast, researcher and writer. Apart from writing he is also a researcher, with specialization on thin films for electrodes in solar cells.

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