Lesson 1.2. Classifications of Matter
Learning Objectives
At the end of the lesson, you (student) should be able to:
1. Differentiate between pure substances and mixtures.
2. Differentiate elements from compounds.
3. Classify the different kinds of mixtures.
4. Differentiate the different kinds of compounds.
Learning Time (Acquire New Knowledge)
Now that you have given your initial understanding based on the above concepts, this time
let’s get to know and understand more about the different classifications of matter.
Substances and Mixtures
A substance is a form of matter that has a definite (constant) composition and distinct
properties. Examples are water, ammonia, table sugar (sucrose), gold, and oxygen.
Substances differ from one another in composition and can be identified by their appearance,
smell, taste, and other properties.
A mixture is a combination of two or more substances in which the substances retain
their distinct identities. Some familiar examples are air, soft drinks, milk, and cement. Mixtures
do not have constant composition. Therefore, samples of air collected in different cities would
probably differ in composition because of differences in altitude, pollution, and so on.
Mixtures are either homogeneous or heterogeneous.
When a spoonful of sugar dissolves in water we obtain a homogeneous mixture in
which the composition of the mixture is the same throughout. If sand is mixed with iron filings,
however, the sand grains and the iron filings remain separate (Figure 3). This type of mixture
is called a heterogeneous mixture because the composition is not uniform.
Any mixture, whether homogeneous or heterogeneous, can be created and then
separated by physical means into pure components without changing the identities of the
components. Thus, sugar can be recovered from a water solution by heating the solution and
evaporating it to dryness.
Condensing the vapor will give us back the water component. To separate the iron-
sand mixture, we can use a magnet to remove the iron filings from the sand, because sand is
not attracted to the magnet [see Figure 4]. After separation, the components of the mixture
will have the same composition and properties as they did to start with.
