Compounds as Pure Substances
Compounds are indeed pure substances, even though they are made up of more than one type of atom. Let's delve into the details of why compounds are considered pure substances.

Chemical Composition
- Compounds are composed of two or more different elements chemically bonded together in fixed ratios. These elements combine to form a unique substance with distinct properties.
- The chemical composition of a compound remains constant, regardless of its source or method of preparation.

Homogeneity
- Compounds exhibit homogeneity, meaning that they have a uniform composition throughout. This uniformity distinguishes compounds from mixtures, where different substances are physically mixed together.

Distinct Properties
- Compounds have unique chemical and physical properties that differ from those of their constituent elements. These properties arise from the specific arrangement of atoms within the compound.

Separation
- Unlike mixtures, compounds cannot be separated into their constituent elements by physical means such as filtration or distillation. Chemical reactions are required to break the bonds holding the elements together.

Purity
- Due to their fixed composition and uniformity, compounds are classified as pure substances. They have a specific chemical formula that defines their structure and properties.
In conclusion, compounds may consist of multiple elements, but their chemical composition, homogeneity, distinct properties, inability to be physically separated, and purity make them pure substances.