The Atom 'mikrotartalom' is a helper to discover the smallest cell of material, which are not seenable for us.  The Atom helps you to explain the definiton of the atom, the atomic numbers, moreover it gives 3 small tasks to improve yourself.

The properties of a given substance depend on the state functions: pressure and temperature. For example water can be ice, liquid water and water vapour, so there is 3 matter of state: solid, liquid and gas.

Energy relations of dissolution illustrated by an experimental example.