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Two clear bottles look the same. One holds sea water. One holds lab water, which has almost nothing else in it. How can you tell?

This is Chapter 8, Nature of Matter: Elements, Compounds, and Mixtures. It asks what kind of substance you are holding.

What this track covers

• Pure and mixed — one substance, or more than one.
• Elements — substances that cannot be broken into simpler ones.
• An agreed short name — one symbol for each element.
• Compounds — elements joined in a fixed ratio.
• Mixtures — substances together, not joined.
• Telling them apart — iron and sulfur, mixed and then heated.
• Sorting everyday things into piles — element, compound or mixture.
• Atoms joined as one particle — molecules of hydrogen, oxygen and water.
• Which states are mixed — a mixture sorted by solid, liquid and gas.
• Between a metal and a non-metal — metalloids, like silicon.
• Minerals from the ground — native minerals and compound minerals.
• Same acid, different gas — word equations for the acid test.
• What counts as matter — mass, space, and what is not matter.

One rule before anything else

A bench is a screen where you test an idea. Every bench here is a simulation, a pretend test. Nothing is mixed, heated or split for real. In a real lab, a teacher is always there. Never taste or smell anything.