Element, compound or mixture?

You will write a function that sorts a substance from three facts: how many kinds of atom it has, whether they are joined chemically, and whether they are in a fixed ratio. The program then sorts six substances.

The idea. An element has one kind of atom. A compound has two or more kinds, joined chemically in a fixed ratio. A mixture has two or more substances, not joined, in any ratio.

Your tasks.

1. If there is one kind of atom, return "element".
2. If the atoms are joined and in a fixed ratio, return "compound".
3. Otherwise, return "mixture".