A substance that cannot be chemically broken down into simpler substances is called an element.
Elements are the building blocks of matter. Each element is a pure substance made up of a unique type of atom, and they cannot be transformed into simpler substances by ordinary chemical processes. For example, elements like hydrogen, oxygen, and carbon have distinct properties and cannot be broken down further without a nuclear reaction.
There are currently 118 known elements, and they are organized in the periodic table. Understanding elements is fundamental in fields like chemistry, physics, and biology, as they form the basis for all chemical compounds and organic life.