Section 1 f) Summary

Ionic compounds are formed when a metal and non-metal meet, and there is a transfer of electrons. This causes both atoms to become oppositely charged ions, which experience strong forces of electrostatic attraction towards each other.

Ionic compounds are not easily broken apart, their strong forces of attraction mean they have high melting and boiling points: they require a lot of energy to break the bonds.
The compounds, as a solid, form a giant ionic lattice structure. It is a lattice, meaning it is regular which results in the solids forming into translucent, geometric crystals (think of salt).

This can be represented at a molecular level using the following diagram:

The positive and negative ions alternate, because like attractions repel and opposites attract. Therefore, when force is applied to an ionic solid, it breaks easily: it is brittle. This is because when the ions are forced to move, they don't slide over each other easily, they get close to a similar charge, causing a force of repulsion and making it break apart easily.

It is important to know the charges of ions seen commonly in this topic. We can deduce the charge based on the number of outer shell (valence) electrons (if it has two, it will lose them, if it has six, it will gain two, etc.)
The following periodic table is a useful guide on the trends: