1. Elements: These are the simplest forms of matter that cannot be broken down into simpler substances by chemical means. Examples include gold, oxygen, and carbon.
2. Compounds: These are formed when two or more elements chemically combine in a fixed ratio. Examples include water (H₂O), salt (NaCl), and sugar (C₁₂H₂₂O₁₁).
Therefore, pure substances can either be elements or compounds.
