Chemistry is the study of matter and the changes it undergoes, with the atom as its basic functional unit.

Matter is anything that occupies space and has mass.

Matter is classified into three main types:

• 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, not chemically bonded.

Classification of Matter:

• Pure Substances (Single Composition): Elements and compounds with a fixed composition. Elements cannot be separated into simpler substances by chemical means, while compounds can be separated into elements.

• Mixtures (Variable Composition): Physical combinations of two or more substances. Mixtures can be homogeneous (uniform composition, e.g., Gatorade) or heterogeneous (non-uniform composition, e.g., salsa).

Examples:

• Gatorade: Homogeneous mixture (solution).

• Crystalline sugar: Pure substance (compound).

• Lead wire: Pure substance (element).

• Salsa: Heterogeneous mixture.

Application: Identifying substances as pure substances or mixtures helps in understanding their properties and methods of separation.