Objective
1. Students will define element and give examples and identify their
symbols.
2. Students will define pure substance.
3. Students will define mixture, solution, solute, and solvent.
4. Students will define molecule, diatomic molecule, and compound.
II. Elements, Mixtures and Compounds
A. An element is a pure substance that can not be broken down by
physical or chemical means into a simpler substance. It is
composed of atoms that maintain the properties of that element.
Some elements are gold (Au), aluminum (Al), hydrogen (H),
helium (He), and carbon (C).
B. A pure substance is made of only one kind of matter and has
definite properties. A pure substance can be elements or
compounds.
C. A mixture is two or more substances together that are not
chemically combined. A mixture can be separated or broken
down into the substances that made it. A solution is a mixture that
is integrated so well that it is difficult to distinguish the substances
that made it. A solution can be separated or broken down into the
substances that made it. A solute is the part of a solution that gets
dissolved while the solvent is the part of the solution that does the
dissolving.
1. Water is called the universal solvent because it can dissolve
almost anything.
D. A molecule is the smallest part of a substance that still maintains
the properties of that substance. A molecule is a particle made of
two or more atoms bonded together. A molecule can be broken
into simpler substances by chemical means. A diatomic molecule
is a molecule made of two of the same atoms such as O2. A
compound is a substance that is composed of two or more
elements chemically combined in a specific ratio. A compound is
a pure substance that contains only one kind of molecule and can
only be broken down into its simpler substances by a chemical
reaction.