Elements are substances which cannot be broken down into anything else, because they only have 1 type of atom. Elements are those which can be found in the periodic table:
The Rows are called periods and the columns are called groups; in group 1 are found very reactive metals, in group 8 are found those gasses which are very unreactive.
Mixtures
Mixtures are easy to separate, this is because in a mixture there really is no new substance made, in other words the substances are not bonded together, be it elements and/or compounds. You can use distillation, filtration, evaporating, magnetism or chromatography to separate them.
Compounds
These are very difficult and sometimes impossible to separate because of their fixed composition of 2 or more elements chemically bonded together. When a compound is created, a chemical reaction occurs, you can tell this is happening because you can see a light, the smell that is given out, the change in temperature, the colour changes, there are bubbles (a gas is given out) and/or a new substance is made.
