How it works
This classification of matter chart starts with Matter and asks two yes or no questions. Each answer leads to a blank box: name the six terms, or print the chart blank for class.
Read the full guide
Read the chart from the top
Start at Matter. If physical means such as filtering or boiling off a liquid can separate it, it is a mixture; if not, it is a pure substance. A mixture that is the same all through is homogeneous, and one that varies is heterogeneous. A pure substance that a chemical change can break down is a compound; one that cannot is an element, such as iron or oxygen.
- Salt water is a homogeneous mixture: you cannot see the salt, but boiling off the water leaves it behind.
- Water is a compound, not an element: it is made of hydrogen and oxygen.
Questions and answers
What are the four main types of matter?
Elements, compounds, homogeneous mixtures and heterogeneous mixtures. Elements and compounds are pure substances; the other two are mixtures.
What is the difference between a mixture and a compound?
A mixture can be separated by physical means, and its parts keep their own properties in amounts that can vary. A compound is elements chemically combined in a fixed ratio, and only a chemical change breaks it down.
Is air a homogeneous or heterogeneous mixture?
Clean air is a homogeneous mixture: its gases are evenly mixed, so any sample has the same make-up. Oil and vinegar dressing is heterogeneous, because one drop can be mostly oil and another mostly vinegar.