What is the main characteristic of an element in chemistry?

The main characteristic of an element in chemistry is that it cannot be decomposed into simpler substances. Elements are the fundamental building blocks of matter and consist of only one type of atom. This inability to break down further into simpler components distinguishes them from compounds and mixtures. Compounds are composed of two or more different elements that are chemically bonded together, while mixtures are combinations of two or more substances that retain their individual properties. Thus, knowing that an element is the simplest form of matter that cannot be divided further into any other substances helps solidify the concept of what constitutes an element in the field of chemistry.