Matter and Its Classification: Introduction to General Chemistry

Matter and Measurement

Introduction to Chemistry

Chemistry is the study of matter and the changes it undergoes. Matter is defined as anything that occupies space and has mass. The basic functional unit of matter is the atom.

• Matter: Anything that occupies space and has mass.

• Matter can be classified based on its composition and properties.

Classification of Matter

Matter is classified into three main types based on its composition:

• Element: The simplest type of matter, composed of only one kind of atom.

• Compound: Matter composed of two or more different elements that are chemically bonded together.

• Mixture: Matter composed of elements and/or compounds that are physically mixed together but not chemically bonded.

Classification Table

Matter	Single Composition	Variable Composition
	Puresubstance	Mixture
	Element Compound	Heterogeneous Homogeneous

Pure substances have a fixed composition and distinct properties. Mixtures contain two or more substances physically combined and can be separated by physical means.

Types of Mixtures

• Homogeneous mixture: Has uniform composition throughout (also called a solution).

• Heterogeneous mixture: Has non-uniform composition; different parts can be observed.

Examples and Applications

Consider the following substances:

• Gatorade

• Crystalline sugar

• Lead wire

• Salsa

Classification:

• Gatorade and salsa are homogeneous mixtures.

• Crystalline sugar and lead wire are pure substances.

Practice Questions and Answers

• Which of the following statements is true? - Gasoline is a pure substance. (False; gasoline is a mixture of hydrocarbons.) - Only elements are pure substances. (False; compounds are also pure substances.) - All are homogeneous mixtures. (False; not all listed substances are homogeneous mixtures.)

• Choose the heterogeneous mixture from the list below: - Trail mix (Correct; visibly different components.)

• Choose the homogeneous mixture from the list below: - Fruit salsa (Correct; uniform composition throughout.)

• Classify each of the following as an element, compound, or mixture: - Ammonia, NH3: Compound - Gold bar: Element - Orange juice: Mixture - Wine: Mixture - Saline solution: Mixture

Key Terms and Definitions

• Element: A substance that cannot be broken down into simpler substances by chemical means.

• Compound: A substance composed of two or more elements in fixed proportions.

• Mixture: A combination of two or more substances in which each retains its own identity.

• Homogeneous mixture: A mixture with uniform composition throughout.

• Heterogeneous mixture: A mixture with non-uniform composition.

Formulas and Equations

• Chemical formula for ammonia: $\mathrm{NH_3}$

• General representation of a compound: $\mathrm{A}_x\mathrm{B}_y$

Additional info: Gasoline is a mixture, not a pure substance. Homogeneous mixtures are also called solutions. Elements and compounds are both considered pure substances because they have definite compositions.