What kind of substance cannot be separated into simpler substances by a chemical change?

An element is a pure substance that cannot be broken down into simpler substances through chemical reactions. Elements consist of only one type of atom, which defines their chemical properties. Each element is represented on the periodic table, and they are the fundamental building blocks of matter. Unlike compounds, which consist of two or more different elements chemically bonded together, or mixtures, which are combinations of multiple substances that retain their individual properties, elements remain unchanged and cannot be decomposed into simpler forms. This intrinsic property of elements makes them unique compared to compounds and mixtures, which can undergo chemical changes to create simpler components.