PURE SUBSTANCES
Def.: A sample of matter, either a single element or a single compound, that has definite chemical and physical
properties. It cannot be broken down into simpler substances by physical means.
Substance
Smallest Particle
ELEMENT
ATOM
 A substance that cannot
be separated or broken
down into simpler
substances by chemical
means.
 Each has unique
characteristic properties.
COMPOUND
 A substance made up of
atoms of two or more
different elements
joined by chemical
bonds.
 Each has unique
characteristic properties
different from those of
the elements that form
it.
Unit 2 (Ch.5) - Structure of Matter
The smallest unit of an
element that maintains
the properties of that
element.
3 Common
Examples
Hydrogen (H)
Oxygen (O)
Carbon (C)
Picture
Hydrogen Atom
QuickTime™ and a
TIFF (U ncompressed) decompressor
are needed to see this pi cture.
MOLECULE
A group of atoms held
together by chemical
forces; a molecule is
the smallest unit of
matter that can exist by
itself and retain all of a
substance’s chemical
properties.
Water (H2O)
Carbon Dioxide
(CO2)
Sodium Chloride, Salt
(NaCl)
Water (H2O) Molecule
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Bach
10//05/09
PURE SUBSTANCES
Def.:
Substance
Unit 2 (Ch.5) - Structure of Matter
Smallest Particle
3 Common
Examples
Bach
Picture
10//05/09