What is the definition of an element?

An element is defined as a substance that cannot be broken down into simpler substances by chemical means. This definition highlights the fundamental nature of elements in chemistry. Elements are the basic building blocks of matter and consist of only one type of atom. For instance, gold (Au) or oxygen (O) are examples of elements, and no chemical process can separate them into simpler substances.

Understanding this definition is crucial because in the broader context of chemistry, elements differ fundamentally from compounds and mixtures. Compounds are made up of two or more elements bonded together and can be broken down into those elements through chemical reactions. Mixtures consist of various substances that retain their individual properties and can typically be separated by physical means. Thus, the uniqueness of an element lies in its indivisibility by chemical processes, making this definition essential for grasping foundational concepts in chemistry.