* Elements are pure substances that cannot be broken down into simpler substances by chemical means (e.g., gold, oxygen, carbon).

* Compounds are formed when two or more elements chemically combine in a fixed ratio (e.g., water (H₂O), sodium chloride (NaCl)).

* Mixtures are combinations of two or more substances that are not chemically bonded and can be separated by physical means (e.g., salt and pepper).

Sodium acetate (NaC₂H₃O₂) is formed by the chemical combination of sodium (Na), carbon (C), hydrogen (H), and oxygen (O). It has a fixed ratio of these elements, and it cannot be separated into its constituent elements by simple physical means.