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Structure of an Atom - Micro teaching Session

Livingsta shares her positive experience in business administration, customer service, and education.


This little unit here is a micro teaching that I delivered during my PTLLS (Preparing to teach in the lifelong Learning Sector course at Level 3. I thought I would share this, so candidates who wish to do a micro teaching will get an overview of what to prepare and how to prepare. When I was researching for micro teaching samples on the internet during my course, I could not get any helpful specimen. I hope this helps anyone looking for samples and also will help with any students looking for references, or preparation of assignments about atoms.


Session Objectives:

By the end of this session, learners will be able to:

•Describe that matter is made of atoms and explain the structure of an atom

•Learners will state the charge of each particle in an atom, and explain how they are arranged to make up an atom.

•Learners will identify the atomic number and mass number of atoms in the Periodic Table of the Elements and calculate the number of protons, neutrons and electrons in an atom with the help of Periodic table.


Basic Atomic Structure

What are Atoms?

Atoms are the smallest unit of matter that retain the identity of the substance chemically.

Atoms are particles of elements or substances and they can not be broken down into further individual particles without changing the chemical properties of the substance.

Atomic Structure

Atomic Structure

Atomic Structure

Atoms are composed of 2 regions:

Nucleus: the center of the atom that contains the mass of the atom

Electron cloud: region that around the nucleus and it occupies almost most of the space in the atom


For example, if you have 1 ton, 1 gram or 1 atom of gold, all of these units have the same properties. We can break down the atom of gold into smaller particles, however, when we do, the atom looses its chemical properties.

For example, if you have 50 identical mobile phones (same make, colour, model). They all behave like mobile phones, let you make calls, receive calls, texting and other features etc., depending on the specification. However if you dismantle one or more of these and take the case off, the screen off, the battery off the other little boards and chips off, the mobile phone no longer behaves like a mobile phone. Instead it is different parts lying around and you can't call them mobile phone and they don't behave like one.

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What is in the Nucleus?

There are three subatomic particles in general. Out of the three, two of them are found in the nucleus. They are:

The Protons that are positively charged

The Neutrons that are neutrally charged (have no charge)

These Protons and neutrons are collectively called nucleons (Protons + neutrons = nucleons)


What is in the Electron Cloud?

So where is the third subatomic particle? The 3rd subatomic particle is located outside the nucleus called the orbital region but in the electron cloud and it is called:

The Electron which is negatively charged and has relatively no mass (almost zero)

The Structure of an atom

The Structure of an atom


All matter is made up of atoms.

To be clear, one can visualise an atom like a tiny solar system. Similar to the planets revolving around the sun, the atom has a central mass which is in the centre, called the nucleus (protons with positive electric charge + neutrons which are electrically neutral) which makes up for most of the mass or weight of the atom. Similar to the planets revolving around the Sun, there are electrons revolving at very high speed around the nucleus. These electrons (negative electric charge) are very small and light.

Now that these atoms are really small, one might have doubts or questions in mind as to: Are there particles or pieces of matter that are smaller than atoms?

The answer is, "Yes" sure there are !!!

Atoms are composed of particles like neutrons, electrons, and protons.


There are even smaller particles, I mean smaller than atoms (which are considered to be the smallest particles) moving around in atoms and these can be found inside the protons and neutrons. The most common ones are called quarks (That is what the scientists have named them!). There are Up quarks (charge +2/3) and Down quarks (charge -1/3) and these quarks join together to form protons and neutrons.

Structure within an atom

Structure within an atom


How do these particles interact?

Now let us see here, how these particles interact with each other inside tha atom. In the diagram to the right, you can see that each particle has either a "+" sign, a "-" sign, or a “0" next to it, and that sign refers to the charge of the particle.

As we have seen above,

•The electron always has a "-" sign or negative charge.

• The proton always has a "+" sign or positive charge.

• So the above implies that if the charge of an entire atom is "0", that clearly means that there are equal numbers of positive and negative particles, which is equal numbers of electrons and protons. So these charges cancel out each other or neutralise thereby giving the atom no charge or making it neutral (charge free).

The third particle is the neutron. It has a neutral charge (a charge of zero).


How do the subatomic particles balance each other?

Summarising the above, we see that in an atom:

The number of protons = the number of electrons

•For example, if there are 25 protons present in an atom then there will be 25 electrons inside the atom so that they balance the overall charge of the atom thereby making the atom neutral

The number of neutrons is not a problem, as the neutrons have no charge; therefore they do not have to equal the number of protons or electrons.

Now this implies something !

Different number of neutrons, but same number of protons and electrons ????? Have you heard about "Isotopes"?

I will be writing down a detailed hub about this soon !


Periodic Table


Electrons, Protons And Neutrons | Standard Model Of Particle Physics

How do we know the number of subatomic particles in an atom?

In order to calculate the number of subatomic particles, we need to have a method. So we denote certain factors as follows:

Atomic number (Z): which is the number of protons in an atom

  • Therefore No of protons = ATOMIC NUMBER of the atom (Z)

Mass number (M): the number of protons and neutrons in the nucleus

  • Therefore MASS NUMBER of the atom (M) = No of protons + no of neutrons


So now looking at the factors above, let us do a small calculation: Look at the diagram to the right. Let us find out, how many protons and neutrons this atom has got?

From the diagram we see:

The atomic number of the atom = Number of protons = 11

The mass number = Number of protons + Number of neutrons = 23

So if there are 11 protons, there must be 12 neutrons for the total to add up to 23 to make up the mass number.

Therefore, the total number of neutrons for the atom to the right is 12.


What are Atoms?


  • Atoms are the basic building blocks of all matter in this universe
  • Atoms are composed of protons (+ve charge), electrons (-ve charge) and neutrons (0 charge)
  • Protons and neutrons form the nucleus.
  • Electrons revolve around the nucleus in orbitals and this region is called electron cloud
  • The number of protons in the nucleus of the atom = The atomic number (Z).
  • The number of electrons in a neutral atom = The number of protons.
  • The mass number of the atom (M) = The sum of the number of protons + number of neutrons in the nucleus.
  • The number of neutrons = Mass number of the atom (M) - Atomic number (Z).

Learners can

•Describe that matter is made of atoms and explain the structure of an atom

•State the charge of each particle in an atom, and explain how they are arranged to make up an atom.

•Identify the atomic number and mass number of atoms in the Periodic Table of the Elements and calculate the number of protons, neutrons and electrons in an atom with the help of Periodic table.



livingsta (author) from United Kingdom on December 28, 2015:

Amitdw, thank you. I am glad that you found this useful!

livingsta (author) from United Kingdom on December 28, 2015:

lasya madhuri , thank you so much for reading and the feedback. I am glad that this was helpful!

lasya madhuri on August 21, 2015:

Excellent explanation livingsta really it is very useful to study about the structure an atom you have done a great job.

amitdw on June 14, 2015:

Great explanation for students. Thanks for sharing.

livingsta (author) from United Kingdom on June 21, 2014:

Thank you MoiraCrochets, I'm glad that you found this helpful :)

Moira Durano-Abesmo from Sagay, Camiguin, Philippines on November 03, 2013:

The way you divided the information about atoms makes its simpler to understand. This is a good hub.

livingsta (author) from United Kingdom on November 13, 2012:

Thank you for the read and appreciation VinodkPillai. Thank you for the votes too!

Vinod from Hyderabad, India on November 12, 2012:

Oh this was beautiful! I love teaching (and did teach for a while) and had an interest and education in science. So I enjoyed reading this micro teaching sample, which I think will be very useful for anybody involved in teaching. Voted up and useful.

livingsta (author) from United Kingdom on October 11, 2012:

Thank you so much Unknown Spy!

DragonBallSuper on October 10, 2012:

very informative livingsta. i love how you explained these things.

livingsta (author) from United Kingdom on September 17, 2012:

Thank you Nell, I really appreciate! :-)

Nell Rose from England on September 16, 2012:

Fascinating livingsta I love quantum physics, and atoms fascinate me, this was a really good guide to explaining the atom, wonderful! voted up and shared! nell

livingsta (author) from United Kingdom on August 28, 2012:

Thank you Rahul. I will look into your suggestion. Thanks a lot!!!

Jessee R from Gurgaon, India on August 20, 2012:

Now you have given a good amount of detail.... and I liked that you discussed about quarks,... 'cause most of the textbooks still do not discuss them...

Useful read... I think the schrodinger equation will give a bright light on the discussion of the electron cloud :)

Nice article

livingsta (author) from United Kingdom on July 29, 2012:

Thank you Cheeky Girl, for the appreciation !

Cassandra Mantis from UK and Nerujenia on July 29, 2012:

Great Hub! Nice to see a big subject like this getting a Hub to itself! Awesome!

livingsta (author) from United Kingdom on July 29, 2012:

Thank you so much Thesingernurse :)

Tina Siuagan from Rizal, Philippines on July 29, 2012:

This is a very simple way to explain important points about atomic properties. I like how you included a summary of points in the end. If you're doing a microteaching, or any form of teaching session for that matter, it is always good to incorporate key points in the summary to reinforce knowledge and improve retention.

Sharing this topic to everyone. :)

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