* Pure Substances: These are substances that have a fixed chemical composition and unique properties. They cannot be broken down into simpler substances by physical means. Examples include water (H₂O), table salt (NaCl), and gold (Au).
* Mixtures: These are combinations of two or more pure substances that are not chemically bonded. They can be separated by physical means. Examples include saltwater, air, and sand.
However, there are other ways to classify substances, such as:
* Elements: These are the simplest forms of matter and cannot be broken down into simpler substances. They are found on the periodic table. Examples include oxygen (O), carbon (C), and iron (Fe).
* Compounds: These are formed when two or more elements chemically combine in a fixed ratio. Examples include water (H₂O), carbon dioxide (CO₂), and sugar (C₁₂H₂₂O₁₁).
* Homogeneous Mixtures: These mixtures have a uniform composition throughout. Examples include saltwater and air.
* Heterogeneous Mixtures: These mixtures have a non-uniform composition. Examples include sand and water, or a salad.
The classification you use depends on the context and what aspects of the substance you are interested in.
