Dimitri Mendeleev was inspired primarily by the work of Antoine Lavoisier and his work on writing the first extensive list of known elements. Lavoisier also collaborated in the construction of the metric system and worked to develop a better nomenclature for chemical compounds which parts are still used today.
Well a mixture is less permanent and also it can be easily taken aprt where a compound does the opposite of those things.
Hope I helped :)
The equilibrium constant is a value which represents the equilibrium of a reaction. It is a reaction quotient when the reaction reached equilibrium. If Keq is greater than 1, the mixture contains mostly the products. On the other hand, if Keq is less than 1, the mixture contains the reactants. For this case, the mixture contains mostly products.