Compound
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
A compound is a pure substance of two or more elements combined in a fixed ratio, separable only by chemical change.
Show
Heating mercury(II) oxide breaks it into mercury and oxygen, revealing it was never a blend of loose ingredients.
Watch for
A compound's properties differ completely from its elements — water is a stable liquid built from a flammable gas and one supporting combustion.