Final answer:
The basic forms of matter, which include solids, liquids, and gases, are known as the phases of matter. Solids have a set shape and volume, liquids have a set volume but adapt their shape to their container, and gases have neither a definite shape nor volume. Matter can be categorized as pure substances or as homogeneous and heterogeneous mixtures.
Step-by-step explanation:
The basic forms of matter are known as the common phases of matter, which include solids, liquids, and gases. Solids have a definite shape and volume, making them rigid. Liquids are able to flow and take on the shape of their container while maintaining a definite volume. Gases expand to fill their container, having neither a definite shape nor a fixed volume.
When categorizing matter, it is important to distinguish between pure substances and mixtures. A pure substance has uniform properties and a composition that does not vary throughout the sample. In contrast, mixtures are the physical combinations of two or more elements and compounds. There are two types of mixtures: homogeneous, which have uniform composition and properties throughout, and heterogeneous, which do not. This categorization helps in understanding the vast diversity of materials we encounter daily.