elements:
a pure substance containing only one kind of ______.
an element _______ be separated into simpler materials (except during nuclear reactions).
over 100 existing elements are listed and classified on the ________.

compounds:
a pure substance containing two or more kinds of _______.
the atoms are _______ combined in some way.
compounds ___________ be separated by physical means.

mixtures:
two or more_________ or __________ NOT chemically combined.
mixtures can be uniform(called______________) and are known as solutions
mixture can also be non-uniform (called ______________).