Atom And Elements

Atoms are the building blocks of everything in the universe. They are so small that you can only see them with an incredibly powerful microscope. They have a few different bits that make them up, as you can see in the diagram below:

Atom structure diagramThe Nucleus

  • Is in the middle of the atom
  • It contains protons, which have a positive charge
  • It contains neutrons which have no charge at all (i.e. are neutral)
  • Overall the nucleus has a positive charge….as you would expect because of the protons.
  • It’s very small compared to the rest of the atom…about the size of a pea in a football stadium

The Electrons

  • They are really small and whizz around the nucleus
  • They have a negative charge
  • They occupy “shells” or “levels” around the nucleus

This last fact is incredibly important – in fact it explains the whole of chemistry and we’ll be going into it in a lot more detail.

Some Other Facts About The Atom

  • The number of protons equals the number of electrons
  • The charge on a proton is the same but opposite to the charge of an electron
  • As such an atom is neutral overall
  • If some electrons are added or removed then the atom becomes positively or negatively charged and is called an ion


These are substances that are made up of only ONE TYPE of atom.

Atoms can have different numbers of protons, neutrons and electrons but it is the number of protons that decide what type of atom it is.

The periodic table shows all of the elements we know about. It includes things like iron, copper and nitrogen – you’ve heard of them right?