CLASSIFICATION AND PROPERTIES OF MATTER
INTRODUCTION
Chemistry is often defined as the study of matter. Associated with this concept of matter are
terms such as substance, compound, element, mixture, etc. Matter is also described as possessing
certain properties, e.g. smell, color. We distinguish between physical or chemical properties.
Substances can also undergo changes, some of which are classified as physical changes and others as
chemical changes. Terms such as these need to become part of the vocabulary of students who wish
to undertake a serious study of chemistry. In the following sections, definitions will be given for
these concepts and are illustrated in a series of simple exercises.
DEFINITIONS
Matter is anything that has mass and occupies space. Matter can exist in three forms or phases:
solids, liquids, or gases.
A substance is defined as matter which is homogeneous and of which all parts are alike.
Substances are either elements or compounds.
Elements are pure substances which cannot be decomposed into simpler substances by chemical
means. Some familiar elements are oxygen, gold, sulfur, and iron.
Compounds are pure substances that are composed of two or more elements. Substances such as
water, salt, and sugar are simple examples of compounds. On the other hand, wood or a piece of
marble are not homogeneous and therefore not pure substances or compounds. They are called
mixtures.
Mixtures are defined as matter which consists of two or more substances mixed together. A
mixture can be either homogeneous or heterogeneous. In a heterogeneous mixture several difference
components can be detected with the unaided eye. Marble is not homogeneous, you can see
different colored components. However, salt dissolved in water produces a perfectly homogeneous
mixture.
The relationship between the concepts introduced above is shown in Figure 1.
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INTRODUCTION
Chemistry is often defined as the study of matter. Associated with this concept of matter are
terms such as substance, compound, element, mixture, etc. Matter is also described as possessing
certain properties, e.g. smell, color. We distinguish between physical or chemical properties.
Substances can also undergo changes, some of which are classified as physical changes and others as
chemical changes. Terms such as these need to become part of the vocabulary of students who wish
to undertake a serious study of chemistry. In the following sections, definitions will be given for
these concepts and are illustrated in a series of simple exercises.
DEFINITIONS
Matter is anything that has mass and occupies space. Matter can exist in three forms or phases:
solids, liquids, or gases.
A substance is defined as matter which is homogeneous and of which all parts are alike.
Substances are either elements or compounds.
Elements are pure substances which cannot be decomposed into simpler substances by chemical
means. Some familiar elements are oxygen, gold, sulfur, and iron.
Compounds are pure substances that are composed of two or more elements. Substances such as
water, salt, and sugar are simple examples of compounds. On the other hand, wood or a piece of
marble are not homogeneous and therefore not pure substances or compounds. They are called
mixtures.
Mixtures are defined as matter which consists of two or more substances mixed together. A
mixture can be either homogeneous or heterogeneous. In a heterogeneous mixture several difference
components can be detected with the unaided eye. Marble is not homogeneous, you can see
different colored components. However, salt dissolved in water produces a perfectly homogeneous
mixture.
The relationship between the concepts introduced above is shown in Figure 1.
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