2. • A substance is matter that is always made up of the same combination
• There are two types of substances— elements and compounds.
• The composition of elements and compounds doesn’t change. Therefore,
all elements and compounds are substances.
5. • A mixture is two or more substances that are physically blended but are
not chemically bonded together.
• The relative amounts of each substance in a mixture can vary.
• Granite, a type of rock, is a mixture. Granite contains bits that are white,
black, and other colors. Two pieces of granite will have different amounts
of each color bit. The composition of rocks varies.
6. • Air is also a mixture. Air contains about 78 percent nitrogen, 21 percent
oxygen, and 1 percent other substances.
• This composition varies. Air in a scuba tank can have more than 21
percent oxygen and less of the other substances.
7. heterogeneous /
• Rocks and air are examples of the two different types of mixtures—
heterogeneous and homogeneous.
• It’s not always easy to identify a mixture. A rock looks like a mixture, but
air does not.
8. heterogeneous mixtures
• A heterogeneous mixture is a mixture in which substances are not
• Often, you can see the different substances and parts of a heterogeneous
mixture with unaided eyes. Sometimes you can see them only with a
9. heterogeneous mixtures
• Blood looks evenly mixed—its color and texture are the same throughout.
• Suppose you compare two samples of blood under a microscope. They
will look different. The samples will contain different amounts of the
components (plasma, rbc, wbc, platelets)
10. homogeneous mixtures
• A homogeneous mixture is a mixture in which two or more substances
are evenly mixed on the atomic level but not bonded together.
• The individual atoms or compounds of each substance are mixed.
• Air is a homogeneous mixture.
• Another name for a homogeneous mixture is solution.
also called solutionscan see different parts with an unaidedfruit saladlooks the same throughoutsalt watersubstances not evenly mixedbloodevenly mixed but not bondedgraniteone colour and texturesoilsugar water
12. how do compounds and
• The substances that make up a mixture are not chemically bonded.
• Mixing is a physical change. The substances that exist before mixing still
exist in the mixture.
13. how do compounds and
• Substances that make up a mixture are not changed chemically.
• You can observe some of their properties in the mixture.
• Sugar water is a mixture of two compounds—sugar and water. After the
sugar is mixed in, you can’t see the sugar in the water, but you can
still taste its property of sweetness. You can also observe some
properties of the water, such as its
14. how do compounds and
• The properties of a compound can be different from the properties of the
elements that make it up.
• Sodium and chlorine bond and form table salt. Sodium is a soft, opaque,
silvery metal. Chlorine is a greenish, poisonous gas. You cannot observe
any of these properties in table salt.
15. how do compounds and
• The substances that make up a mixture are not bonded together.
• As a result, you can separate them from each other using physical
• The physical properties of one substance are different from those of
another. You can use these differences to separate the substances.
• In contrast, you can separate compounds only by a chemical change that
breaks the bonds between the elements.