Final answer:
Atoms are the building blocks of matter, composed of a single material, and can come in various shapes and sizes.
Step-by-step explanation:
Atoms are the building blocks of matter. They are composed of a single material and can come in various shapes and sizes. Atoms of the same element have identical properties, such as size and mass, while atoms of different elements have different properties. These tiny particles cannot be subdivided, created, or destroyed.