Elements

All material in the universe is made up of the 118 elements of the Periodic Table. These are the building blocks from which countless other materials can be created. Approximately 92 elements exist naturally here on Earth, with others being lab-made synthetically in atomically small proportions.

Subatomic Particles

One particle of any element is called an atom, which itself is made up of sub-atomic particles: protons, neutrons, and electrons

	Relative Mass	Charge
Proton	1	+1
Neutron	1	0
Electron	1/2000	-1

Protons and neutrons are bound together in the nucleus, which is the centre of the atom. These particles both have a relative mass of 1, whilst electrons have a tiny relative mass, only one two-thousandth of a proton or neutron.

This means the total mass of an atom is determined by the total number of protons and neutrons it has.

Atomic number

An element is defined by how many protons it has, known as the atomic number.

The number of protons is equal to the number of electrons in a single atom, but electrons transfer and protons remain in the nucleus.

Electron shells

We can visualise the structure of the atom using this basic model:

It shows protons and neutrons at the centre, orbited by electrons that have been organised in pairs within shells. The number of electrons is equal to the number of protons in a single atom, therefore when we draw an atom, we can follow these rules until the atomic number has been reached:

1^st SHELL: maximum of 2 electrons, spaced opposite each other

2^nd SHELL: maximum of 8 electrons, spaced evenly in pairs

3^rd SHELL: maximum of 8 electrons, spaced evenly in pairs

4^th SHELL: it starts getting complicated… but add in up to 2 electrons for potassium (19 total) and calcium (20 total)

Now you can draw the basic atomic structure of the first 20 elements of the Periodic Table, just from knowing the atomic number!