The Periodic Table: A Beginners Guide for a Confused Mind

With plenty of done-for-you examples and easy-to-digest diagrams!

If you’re staring at this monstrosity…

… thinking to yourself “why did people have to make science so complicated?”, then you’ve come to the right place!

After reading our ultimate beginners guide on the periodic table, you will understand:

• What the periodic table is and why it looks like a disorganised mess of randomly placed boxes.
• The correct way of reading the periodic table to make Year 11 and 12 chemistry easy.
• All the terminology used when talking about the periodic table, such as elements, atoms, periods, groups, valence electrons and valence shells.
• An introduction to further trends in the periodic table you should master to tackle HSC chemistry.

Why Does The Periodic Table Look So Complicated?

Science is about looking at the world around us and understanding how it works through observations and experiments. This is important because we can then use this knowledge to make our lives better. If you think about it, this is what any technology – from air conditioners to medication to airpods – is for.

Science works best when we recognise patterns that occur in nature.

It turns out that we understand science much better when we recognise patterns that occur in nature. The periodic table is designed to help you understand patterns in the behaviour of matter. If we understand those patterns, it then becomes easy to predict what happens when matter interacts. This is why the periodic table is a tool you will need to master if you want to ace Year 11 and 12 chemistry. Even if some topics don’t appear to have any connection, you’ll still find that the periodic table can provide clues and trends that save you from relying on memory alone.

In this guide we’ll be dissecting the periodic table in a way that will help you recognise these patterns and trends.

Let’s begin by exploring…

What Is On The Periodic Table?

Chemistry is the study of the properties and behaviours of matter, so let’s see where we can identify patterns in matter. When we experience the world around us through our senses, we recognise that different things are made of different materials. For example steel looks, smells and feels different to wood. They even sound different when you hit them both with a hammer. But if you imagine yourself zooming into both the materials, you would see that they’re actually both made of the same ‘building blocks’, which we call atoms.

Atoms are the tiny ‘building blocks’ of all the physical material around us; you can think of atoms as fancy LEGO blocks that make everything you see and touch. Below is a simple diagram of an atom.

Atoms are spherical in shape and are made of 3 types of particles (ingredients):

1. Protons: these are particles that have a positive charge of (+1) and are located in the centre of the atom (the main central part of the atom is called the nucleus).
2. Neutrons: these are particles that have a neutral charge of (0) and are also located in the centre of the atom (nucleus).
3. Electrons: these are particles that have a negative charge of (-1) and they orbit around the nucleus; similar to how the earth orbits the sun (it’s a little more complex than but it’s a helpful analogy).

It turns out that positive and negative particles attract each other; this is why the electrons don’t just fly away randomly. Whereas two positive particles or two negative particles repel each other.

Also notice that the protons and neutrons are about the same size (and weight), whereas the electrons are much smaller (and lighter). 

Let’s take another look at the diagram of our atom…

This particular atom has 2 protons (2p) and 2 electrons (2e); the specific name we give for this atom is ‘helium’ and the symbol for it is ‘He’. Notice how helium has the same number of protons and electrons (2p and 2e). One of the general properties of atoms is that they have an equal number of positive protons and negative electrons. 

However, different types of atoms have a different number of protons/electrons. Here are the 4 smallest atoms with 1, 2, 3, and 4 protons/electrons respectively. Helium is the second atom from the left. 

You can see that H has 1p and therefore 1e, He has 2p and therefore 2e, Li has 3p and 3e, Be has 4p and 4e. You can keep going by drawing atoms with 5p, 6p, 7p, etc.

The periodic table is just a fancy (but extremely organised) list of the different types of atoms that exist; each box represents a different type of atom. The top number in each box (above the symbol) is called the atomic number (highlighted in red in the above diagram) and it represents the number of protons present in that atom.

The four atoms in the above diagram (H, He, Li, Be) are highlighted in green on the periodic table below to show you where they are located.

You can see that scientists have discovered 118 different types of atoms. Most of these are naturally occurring but some of them have been synthetically (artificially) made in a lab since they don’t occur naturally by themselves. These synthetically-made elements are ‘unstable’, meaning they tend to naturally break apart into smaller atoms after some time (but that’s a topic for another time).

Another word for ‘type of atom’ is element; thus, we have 118 elements on the periodic table.

Confused on the difference between an atom and an element? Let’s do a…

Quick Example

Here there are 3 hydrogen atoms present (1p and 1e in each atom). You can see that there are 3 separate atoms, but only 1 type of atom present (hydrogen).

Therefore I have 3 atoms but only 1 element present.

The full name for the table is the Periodic Table of Elements. The table is periodic, meaning there are patterns that occur over and over again in certain parts of the table, and it highlights what elements follow those particular patterns (we’ll talk about this in the rows and columns section).

So, first let’s learn…

How to Read the Periodic Table

Each element has its own box on the periodic table.

Let’s look at the information inside these boxes using our helium example.

Inside you find the name (Helium), the symbol for the element (He) and two numbers; there is a 2 and 4.003.

The 2 is called the atomic number and it represents the number of protons in this particular atom. In this case, helium has 2p (and thus 2e).

Now let’s talk about what the 4.003 represents.

There are many ‘versions’ of helium that exist on earth. These are called isotopes. Here are two isotopes of helium.

Helium-4 (2p + 2n)	Helium-3 (2p + 1n)

The mass number of an atom is the number of protons and neutrons present inside the nucleus of an atom; you can think of it as how many balls are inside the nucleus.

The helium atom on the left has 2 positive balls and 2 neutral balls, so the total number of balls is 4. So the mass number of the left helium is 4. This is why we call it helium-4.

The helium atom on the right has 2 positive balls and 1 neutral ball, so the total number of balls is 3. So the mass number of the left helium is 3. This is why we call it helium-3.

The mass number also gives us an idea of the amount of mass present in the nucleus (the mass of the electrons is tiny so it’s safe to ignore their mass for the most part). In this case, the helium-4 weighs around 4 times the mass of a proton/neutron, and helium 3 weighs around 3 times the mass of a proton/neutron.

If we were to take the mass numbers of all the helium atoms on earth and find their average, we would calculate that average to be 4.003. This is why 4.003 is called the ‘average mass number’ or ‘atomic weight’.

So you can see that there is a lot of useful information in the box. Here are the boxes for H, He, Li and Be.

If you scroll back up to the helium-4 and helium-3 atoms in the table above, note that the number of neutrons differs, but they are still considered the same element. This is because the type of atom is defined by how many protons there are in the nucleus. So no matter how many neutrons there are in the nucleus, if the atom has 2 protons, it’s still helium. Conversely, if you know that the atom is helium, you can state for a fact that there are 2 protons in the nucleus.

The periodic table organises these boxes into rows and columns that tell us a lot of information about the behaviour of the elements; this is where you can find those patterns.

So let’s now zoom out and talk about… 

The Significance of Rows and Columns

The periodic table of elements organises these boxes in such a way where the:

1. Elements in the same row have the same number of electron orbits (also called shells).
2. Elements in the same column behave in similar ways.

1. Rows

The rows tell us how many electron orbits (or shells) there are in the atom. This raises the question, what are these electron shells?

When you start considering bigger and bigger atoms, the number of protons and electrons increases (let’s forget neutrons for now). If the number of protons (and neutrons) increase, then naturally the nucleus just gets bigger; pretty simple right?

What about the electrons? How do they organise themselves?

Just like planets are organised in different orbits around the sun, electrons organise themselves in different orbits around the nucleus.

Let’s bring back the helium diagram…

A helium atom has 2 electrons. Those two electrons lie on 1 electron orbit/shell (the grey circle on which the electrons are on).

Let’s take a look at H, He, Li and Be.

You can see that H and He have 1 electron shell. Whereas Li and Be now have 2 electron shells. It turns out that the 1st (smallest) shell can only fit 2 electrons in it, so the additional electrons start organising themselves in the 2nd shell.

Eventually the 2nd shell is filled up with a maximum of 8 electrons (we’ll talk about why in a second), and additional electrons start to organise themselves into the third shell. Check out the diagram of sodium (Na) below.

Sodium has 11 electrons: 2 go in the 1st shell, the next 8 go in the 2nd shell, and the last 1 goes into the 3rd shell.

Notice that electrons are paired up when drawn in the shells, but the reasons are beyond the scope of this guide. For now, let’s just pair electrons up in the shells so it’s easier to count how many we have.

The further out we go, the bigger the shell gets, and therefore the more electrons you can fit in those larger shells.

It turns out that we can calculate the number of electrons that can fit in any shell. The number of electrons that can fit in any shell is given by the formula 2n2, where n is the shell number. Let’s do a quick example showing how to use this…

Quick Example

Consider the 1st shell, therefore n=1.
The number of electrons that can fit in the 1st shell is 2(1)2=2.
Now consider the 2nd shell, therefore n=2.
The number of electrons that can fit in the 2nd shell is 2(2)2=8.
We can do this for all the shells…
The number of electrons that can fit in the 3rd shell is 2(3)2=18.
The number of electrons that can fit in the 4th shell is 2(4)2=32.

The diagram below shows you the number of electrons that can fit in any particular shell (this diagram only goes up to the 3rd shell but you can keep going)…

The rabbit hole of ‘why electrons organise themselves in this way’ is very deep, but if you’re really curious check out orbitals in your chemistry textbook or on Google.

Now, the rows on the periodic table tell you the number of electron shells an atom uses to organise its electrons. So an atom in row 2 has two electron shells, an atom in row 3 has three electron shells, an atom in row 4 has four electron shells and so on. We’ll do some examples in a second.

Keep in mind that the lanthanoids are part of row 6 and actinoids are part of row 7. Notice that the periodic table only goes up to the 7th row. Once you start to get to atoms this big, they tend to naturally separate into smaller more stable atoms very quickly.

So let’s do a few examples exploring the rows…

Quick Example: Helium

Helium is located in the 1st row of the periodic table. It’s located here…
Because it’s in the 1st row, we can safely say that helium only has 1 electron shell. Let’s double check this using the helium diagram…

And you can see that it only has 1 electron shell, as predicted.

Let’s do another one…

Quick Example: Lithium

Lithium is located in the 2nd row of the periodic table. It’s located here…

Because it’s in the 2nd row, we can safely say that lithium has 2 electron shells. Let’s double check this using the lithium diagram…


And you can see that it has 2 electron shells, as predicted.

Let’s do one more…

Quick Example: Sodium

Quick Example: Sodium
Sodium (Na) is located in the 3rd row of the periodic table. It’s located here…
Because it’s in the 3rd row, we can safely say that sodium has 3 electron shells. Let’s double check this using the sodium diagram…

And you can see that it has 3 electron shells, as predicted.

Another term we use to describe a row is a ‘period’, so the period (row) tells us how many electron shells the element has.

Now let’s take a look at…

2. Columns

Elements in the same column chemically react in similar ways. Let’s break it down!

In the world around us, atoms are constantly bumping into each other. When two atoms collide, they often bounce off each other and keep going about their day. But if the conditions are correct, meaning if the right type of atoms hit each other at the right speed and in the right position, they can potentially join together and form something called a compound. A compound is where you have multiple atoms joined together by chemical bonds.

Quick Example: Water

Quick Example: WaterWhen two hydrogen (black) atoms and 1 oxygen (red) atom collide exactly like in the diagram below, they form a compound called water!

Atoms can join together in different ways to form different types of compounds; some common examples include covalent molecules, covalent networks, ionic compounds. In the example above, water is also known as a covalent molecule.

Don’t be confused by those terms, they’re all just fancy names for a bunch of atoms that have joined together in different ways. For example covalent molecules and ionic compounds form very differently to each other, but both are still known as compounds.

Just as atoms can join to form compounds, compounds can join with other atoms/compounds to form larger compounds. Compounds can also break apart to form smaller compounds/atoms. When any of these happen, this is known as a chemical reaction; because things have joined together or broken apart at the chemical level.

When atoms undergo chemical reactions, there is a transfer of electrons that occur between electrons in their outer shells. Another name for outer shells is valence shells. The electrons that are in the outer or valence shell are called valence electrons.

It turns out that atoms that have the same number of valence electrons react in similar ways.

For example, Li (3p/3e) and Na (11p/11e) both have 1 electron in their valence shell. Check out the diagrams below (the protons and neutrons have not been drawn in but they’re there).

Li: 3p, 3e, 3n.	Na: 11p, 11e, 12n.
Li has 1 valence electron in the valence shell (highlighted in red).	Even though Na has more electrons overall, it still has 1 valence electron in the valence shell (highlighted in red).

Therefore, since both Li and Na have a similar valence shell we can safely say Li and Na react very similarly. Here’s how…

Quick Example

Below are two diagrams showing how Li and Na react with Cl (chlorine) to produce the compounds LiCl and NaCl respectively. For each atom, the nucleus is drawn along with their valence electrons ONLY. Different atoms and their valence electrons are drawn in different colours so you can see where the electrons move.

Don’t worry about the mechanics behind the reaction, all you should observe is how Li and Na are behaving in the same way.

Let’s look at how lithium reacts…

You can see how Li has given its valence electron to Cl. So now Li has lost its valence electron.
Now, let’s look at how lithium reacts…

You can see how Na has ALSO given its valence electron to Cl. So now Na has ALSO lost its valence electron.

Both Li and Na reacted in exactly the same way because they have both donated 1 valence electron to Cl.

Notice how both Li and Na are in the 1st column in the periodic table, this is not a coincidence. All the elements in that first column have 1 valence electron and as a result they react in a similar way. Similarly all the elements in the 2nd column react in similar ways… and so on.

The columns that we like to mainly focus on are the following highlighted columns…

We tend to avoid the middle part of the periodic table (called the transition metals) because that’s where things become a little more complicated; there’s a lot we can already learn about the elements in the columns labelled 1-8 in the above periodic table.

Some of these highlighted columns are given special names for various reasons, for example column 8 elements are known as noble gases, column 1 elements (except for hydrogen) are known as alkali metals, column 2 metals are known as alkali earth metals, etc. However, these names are not very important to understand the actual chemistry, so don’t worry about them for now.

The term we use to describe a column is ‘group’, so the yellow column consists of group 1 elements, the orange column consists of group 2 elements, green column consists of group 5 elements, etc.

So, you’ve discovered that elements in the same column react in similar ways because they have the same number of valence electrons. You’ve also learned that group 1 elements have 1 valence electron. Well, if we follow the pattern, group 2 elements have 2 valence electrons, group 3 elements have 3 valence electrons… etc… group 8 elements have 8 valence electrons.

The only exception to this rule is He, which has 2 valence electrons but it’s in group 8. So you may be asking yourself: why isn’t He above He in group 2? Remember, the priority is that we want to put elements in the same column if they behave in the same way. The group 8 elements are so stable and do not react in nature; in other words, they are happy to exist as single atoms. Even though He has 2 electrons in its valence shell (1st shell), it is very unreactive and behaves like the other group 8 elements. Thus, rather than placing it above Be in group 2, it’s placed above Ne in group 8.

So now that you know all about rows and columns…

We can pick out individual elements and say a lot of information about them.

Quick Example

Let’s talk about (i) C and (ii) Mg.

(i) C
C is the symbol for carbon. C is in row 2 and column 4. This means that C uses 2 electron shells to organise its electrons, and it has 4 electrons in its valence (2nd) shell.

(ii) Mg
Mg is the symbol for magnesium. Mg is in row 3 and column 2. This means that Mg uses 3 electron shells to organise its electrons, and it has 2 electrons in its valence (3rd) shell.

That’s all you need to know about the rows and columns!

Let’s zoom out even further and talk about…

Metals, Semi-Metals and Non-Metals

You now know that elements in the same period have the same outer shell and elements in the same group react in the same way.

Because we’ve organised the elements to show patterns of behaviour in rows and columns, the periodic table has naturally arranged the elements itself into 3 main sections.

The elements highlighted green are known as metals; these are elements which tend to lose electrons when they react. The elements highlighted in red are known as non-metals; these are elements which tend to gain electrons when they react. The elements highlighted in blue are known as semi-metals; these are elements which have properties of both metals and non-metals.

If you would like to learn more, let’s take a look at other…

Bonus: Trends in the Periodic Table

Up to this point, we’ve covered some of the trends that occur in the periodic table. These give you the tools to get started with basic chemistry questions at school, including simple reactions.

Five more elemental properties you should consider when looking at the periodic table are:

1. Atomic radius: the distance between the centre of the nucleus and the valence shell.
2. Ionisation energy: how much energy it takes to strip off valence electrons.
3. Electronegativity: a measure of how strong an atom can hold onto its electrons.
4. Reactivity with Water: how reacting an element is with water.
5. Metallic Character: is the element a metal, semi-metal or non-metal.

In chemistry, we like to talk about what happens to these properties as you go down a column and across a row from left to right. This will give you all the tools you need to tackle HSC chemistry.

1. Atomic Radius

As you go down a column, the atomic radius of an element increases. Remember as you go down a row, you’re increasing the number of shells used by the atom to organise electrons. So elements in row 1 use only one shell, elements in row 2 use two shells, elements in row 3 use three shells, and so on..

As you go across a row from left to right, the atomic radius decreases. We cover this in more detail in our classes with plenty of diagrams, but in short, as you go across a row, the number of protons in the nucleus increases. This creates a stronger attraction force between the nucleus and all the surrounding electrons and causes the electrons to shift slightly towards the nucleus. The more protons there are in the nucleus, the stronger the pulling force, therefore the more these electrons will shift (very slightly) towards the nucleus.

Here’s an exaggerated diagram showing how more protons cause the valence electrons (only the valence electrons are drawn) to come slightly closer to the nucleus. 

2. Electronegativity

Electronegativity is a measure of how strongly an atom holds onto its electrons. Since chemical reactions involve electrons in the outer shell of an atom, we’ll talk about how well an atom is holding its valence electrons; we’ll ignore the inner electrons.

As you go down a column, the atomic radius increases, meaning that the valence electrons are further and further away from the nucleus. Even though the number of protons in the nucleus also increases as you go down a column, the larger distance has a much larger effect on attractive force. Since the valence electrons are further and further away, the nucleus is not able to hold onto them strongly. Therefore, the electronegativity of an element decreases down a column, because it’s harder for the element to hold onto its valence electrons when they are this far away.

We’ve already mentioned that as you go across a row from left to right, the attractive force between the nucleus and the valence electrons increases (see atomic radius diagram above). This causes the element to be able to hold onto its electrons more and more strongly, meaning that the electronegativity of an element increases as you go across a row from left to right.

3. Ionisation Energy

The ionisation energy is the amount of energy required to remove the valence electrons of an element (this occurs during a reaction).

As you go down a column, the electronegativity decreases. This means that the attractive force between the nucleus and valence electrons decreases. As a result, it becomes easy to remove the valence electrons. Hence, the ionisation energy decreases down a column.

As you go across, the electronegativity increases. This means that it becomes harder and harder to remove the electrons. Hence, the ionisation energy increases across a row from left to right.

4. Reactivity with Water

The elements that are reactive with water are all of group 1 and group 2; the exceptions are that Be doesn’t react with water and Mg only reacts with steam. So the elements that are more reactive with water tend to be towards the left side of the periodic table.

5. Metallic Character

By now you know that metal is an element that tends to lose electrons in a reaction. You also now know that the lower the electronegativity, the easier it is to strip off the valence electrons. Thus the more metallic the element is because it will have a larger tendency to lose those valence electrons. The elements that have the lowest electronegativity lie in the bottom left of the periodic table, therefore that’s where the metallic character of an element is strongest, this character decreases as you move away from the bottom left of the table. As a result, the metallic character is strongest in the bottom left and weakest in the top right; this makes sense because all the non-metals are on the right side of the periodic table.

This is the simplified explanation of these five trends. We go much deeper and take our time during our weekly classes using full detailed diagrams!

Anyway, let’s do a quick…

Summary:

• The periodic table is just a fancy list of all the elements that exist (that we know of).
• Each box in the periodic table corresponds to a different element.
• Inside each box you have the element’s name, symbol, atomic number, and atomic weight.
• These elements are organised so that elements in the rows/columns follow certain patterns; i.e. elements in the same column react in the same way and elements in the same row use the same number of shells to store their electrons.
• Because we’ve organised the elements into such columns/rows, the periodic table has naturally arranged itself into 3 main sections: metals, semi-metals and non-metals.
• Also as a result, the periodic table is organised nicely to show trends in atomic radius, reactivity with water, electronegativity, ionisation energy and metallic character.
• Master all of the above and you’ll be able to successfully tackle all of Year 11 and 12 chemistry with ease.

Remember, understanding science fully is all about recognising and understanding patterns that occur in nature. The periodic table is organised to help you understand all the patterns that occur in matter. These patterns are the tools you’re going to need to fully master all Year 11 and 12 topics in chemistry.

So, want to ace HSC chemistry? Master the periodic table!

Conclusion

It’s difficult to cover everything about the periodic table in a beginners guide!

This is why in our weekly classes we take things slow and show you exactly how to use the periodic table to your advantage when learning challenging concepts and answering complex chemistry questions; all the way up to the HSC. We break concepts down into simple steps spread throughout the weeks with plenty of practice questions and done-for-you examples. If this guide was helpful and you want to fully master the periodic table from top to bottom, then you are invited to join a class for a week at no cost and no risk!

Call our helpful support on 1300 33 77 88 or fill-in this short 2-minute application for a FREE trial.

See you in class!

Written by one of our tutors: Bartosz Mrowka.