2. Substances
• A substance is matter that is always made up
of the same combination of atom.
• There are 2 types of substances
– Elements*
• *Only made up of one atom
– Compounds
• A compound is matter made of atoms of 2 or more
elements chemically bonded together
• Because the composition of elements and
compounds do not change, all elements and
compounds are substances
3. Mixture
• A mixture is two or more substances
that are physically blended but are not
chemically bonded together.
– *The amount of each substance in a
mixture can vary. (Unlike atoms in a
compound)
4. Mixtures
• Granite
– A type of rock
– Composition of
different rocks
• Air
– Doesn’t look like a
mixture
– 78% nitrogen
– 21% oxygen
– 1% other substances
5.
6.
7. 2 Types of Mixtures
• Heterogeneous Mixture
– Heterogeneous = diverse
• Homogeneous Mixture – Solutions
– Homogeneous = of the same kind; alike
8. Heterogeneous Mixture
• A heterogeneous mixture is a mixture in which
substances are not even mixed.
– Example:
• Granite is a heterogeneous mixture. It is not evenly mixed.
• Often, you can see the different substances and
parts of a heterogeneous mixture with unaided
eyes, but sometimes you need a microscope.
– Example:
• Blood is a heterogeneous mixture.
• It looks evenly mixed, but with a microscope you can easily
see areas with more of one component and less of another.
• Heterogeneous mixture can be hard to tell.
9.
10. Which of the following diagrams
shows a heterogeneous mixture?
11. Solution – Homogeneous Mixtures
• Many mixtures look evenly mixed even when
you view them with a powerful microscope.
• These mixtures are homogeneous
• A homogeneous mixture is a mixture in
which two or more substances are evenly
mixed on the atomic level but not bonded
together.
– The mixture looks evenly mixed because the
individual atoms and compounds are too small to
see
12.
13. Solution
• *Another name for a homogeneous mixture is
a solution.
• Air is a solution. Soda is also a solution.
• Heterogeneous mixture can be hard to tell.
14.
15. How do compounds and mixtures
differ?
• There are 2 important differences between
compounds and mixtures
– Substances in a mixture keep their properties
because they are not chemically changed
• Salt water is a mixture. You can’t see the salt, but
you can taste it in the water.
• In contrast, sodium and chlorine bond to form table
salt.
– Sodium is a soft, opaque, silvery metal
– Chlorine is a greenish, poisonous gas
– Salt has none of these properties
16. – Mixtures can be separated
• Because substances in mixtures are not
bonded, they can be separated using
physical methods
– For example you can boil the water out of salt
water
– The physical properties of one substance will
differ from the other, so they can be physically
separated
• In contrast, compounds can only be
separated by chemical change that breaks
the bonds between the elements.
– Look at the figure on page 339