What Is An Atom? How Small Is It & What Is It Made Of?

So if you have studied science in your school, then the question What is an atom will be a basic one to ask, right? But yet here we are. Asking the very same question once again. Why?

It is because as simple as this question may seem to you, the underlying answer for it is not an easy one. Isn’t it?

But why so?

It is because an atom is something so small that we can not see it through our naked eyes. So what we cannot see, we cannot understand it easily.

What Is An Atom – Definition

But simply put,

An atom is the the smallest constituent of any matter.

What does this even mean? To understand this better,let us take a look at the following example.

Let me say I picked up a piece of graphite. Now as you know, a graphite is made up of Carbon element. So then I start breaking this graphite I picked up into smaller pieces. I will continue to break each of the smaller pieces into further smaller pieces.

So now at this point in time I will ask you this question. How far can I continue to break the graphite? What is the smallest form of graphite I can have?

Then answer for that is – I can break it down until I have only one atom of Graphite left!

So, that is what an atom is. It is the smallest particle of any matter.

But then what will happen if I continue to break the atom even further? The answer is, if you continue to break an atom, it will stop being that element.

Wait…what does that mean?

It simply means that if I break a Graphite atom further, it will stop being a Graphite element all together. It will turn into some other element!

So in other words, an atom is the smallest constituent of any element. If we try to break it any further, it stops being that element any more!

But why does an atom change into other element if broken further? To answer this, we first need to know how an atom looks like. So we will do just that!

What Is An Atom Made Up Of?

An atom, simply put is made up of 3 components:

  • Proton
  • Neutron &
  • Electron

But wait. Didn’t I just say an atom cannot be broken down any further. Then how did we get these 3 components, eh?

Yes, your question is valid. You see, I did not say an atom cannot be further broken down. But instead, what I said is that if you break it any further, it stops being that element.

Do you see the difference?

So in reality an atom can be broken down into protons, neutrons and electrons. But if you want to break it any further, you will have to start removing the total number of protons, electrons and neutrons in it.

But now, removing a few electrons or neutrons from an atom will not change the atom’s element. So if you remove even a single proton from it and you would have changed the element itself!

So this begs us to ask the next question:

What Is An Element?

An element is a substance that is made up of only one type of atom. So when you look at a Periodic Table – which lists all the elements you will find in the universe, you will find a total of 118 elements in it.

Now each of these elements differ from one another based on the number of Protons present in it. So as you can see, it is the number of protons that determine the type of element it is. And as a result, “number of Protons” in an element is so significant that it has its own tern for it – called the Atomic Number.

What Is An Atomic Number?

An atomic number is the total number of protons present in an element. It is represented by the symbol Z. So for example, Hydrogen has an atomic number of 1 (i.e. Z=1). So what it means is that an Hydrogen atom has one Proton in it!

So this calls for another question now. Take a look at the Periodic Table below:

Periodic Table
Periodic Table

Now answer this question for me:

What will happen if if I try to add one more proton into the Hydrogen atom?

As you can see in the periodic table, an Hydrogen atom has the atomic number 1. So it must be having 1 Proton in it. Now when I try to add another Proton to it, I am actually changing it’s atomic number to 2, right?

Then what is the element in the periodic table that has an atomic number of 2? Yep, you are right. It’s Helium!

So you changed a Hydrogen atom to an Helium atom by adding a proton to it! Pretty cool, eh! Feeling like God already?! 😉

So based on this, you now know that can turn an element into any other type of element by just adding or removing protons to it, right?

So then tell me this, how protons do you need to add to Hydrogen(H) atom to turn it into Gold (Au)? If you answered 78, then you are absolutely right!

So does that mean we can easily create Gold out of other elements? Unfortunately NO. This is what alchemists have been trying to do for a long time. But so far they have not succeeded in doing so! 🙁

What Is A Nucleus Of An Atom?

An atom as I told earlier is made up of Protons, Neutrons & Electrons. But how are they packed together inside an atom?

Well you see, an atom consists of a central core to it called a Nucleus. This is where Protons & Neutrons stay packed together. But on the other hand, Electrons are revolving around this nucleus at different orbit levels depending on the type of the element. So this calls for another question:

Why Electrons Revolve Around A Nucleus Of An Atom?

The answer to this is because both Electrons & Protons are electrically charged while Neutrons are neutral. An Electron is said to be negatively charged where as a proton is positively charged.

So as you know, like charges repel each other and unlike charges attract each other. So, electrons are attracted towards the protons and try to fall into the nucleus.

On the other hand, protons which are in the nucleus tend to repel each other, but they are still together because of a force called strong nuclear force. The neutrons in the nucleus will also help the protons by being positioning themselves between two protons.

Can you see atoms through a microscope?

Err…NO, not really. But why?

That is because an atom is extremely small in size. It is so small that it measures just ten-millionth the size of a millimeter, as explained below.

What is the size of an atom?

The size of one single atom is about ten millionth the size of (1/1010) of a millimeter.

Or you can also say it as (1×10−8 cm).

Or it is sometimes even expressed as 100 picometer.

Now that is a number that is so small that we can not even perceive its size correctly. So for us to get a better scale of it, here is a little fodder to trigger your imagination.

Let us take a look at a scale ruler that we find in our geometry box. Here is how it looks like, right?

A scale ruler measuring in centimeters
A scale ruler measuring in centimeters

Now as shown in the pic above, the distance between two taller markings in this ruler is 1 cm. So then here is my question for you.

How many atoms can you fit in a straight line horizontally within this 1 cm space? Do you want to take a guess?

Well, here is your answer in the pic below:

Size of an atom visualized.
Size of an atom visualized.

So as you can see from the above image, we can stack up to 10,00,00,000 or 108 atoms in a row within a size of 1cm!

Now isn’t that something!


So this was just a basic introduction to what an atom is and how it looks like. There are many more concepts related to atom that we could not discuss here as the article started to grow too big. So I will be covering more about it in the future articles.

Learning about the fundamentals or basics of electricity is a must for someone who is trying to get into electronics using boards like Arduino or Raspberry Pi. So this article should have set you in the right direction to learn the basics of it.

Now if you still have any questions related to it, leave a comment below this article and I will try my best to answer them. Alright?

So until next time, take care and happy learning! 🙂

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