* Elements are the purest form of a substance. They cannot be broken down into simpler substances by chemical means. Think of them as the building blocks of matter.
* Substances can be elements, compounds, or mixtures.
* Compounds are formed when two or more elements chemically combine in a fixed ratio. For example, water (H₂O) is a compound made of hydrogen and oxygen.
* Mixtures are combinations of two or more substances that are not chemically bonded. They can be separated by physical means. For example, salt and pepper is a mixture.
Therefore, only the individual entries on the periodic table represent elements. The periodic table doesn't contain compounds or mixtures.
