Section 15-3

Two or more substances that have been combined, but not chemically changed. In salt water, the salt and the water keep their own properties. This is a mixture. A mixture can contain equal numbers of substances or different amounts.

A mixture can be separated by physical means. The mixture’s properties are not chemically combined. Mixtures can be separated by boiling (evaporation) and filtering.

Section 15-4

Making a mixture The substances have been combined, but not chemically changed. Each substance keeps its own properties. Ex. A mixture of sulfur and iron fillings: sulfur is a nonmetallic yellow powder and iron fillings are magnetic slivers of grey metal. You can separate this mixture by using physical means, a magnet.

Making a compound Made up of more than 1 element. The elements are chemically combined. Ex. Iron sulfide is a compound. It contains sulfur and iron which have been heated together to combine the 2 elements chemically. This compound cannot be separated by physical means.