What are the simplest forms of matter called?

The simplest forms of matter are called elements. Elements are fundamental substances that cannot be broken down into simpler substances by chemical means. Each element consists of atoms, which are the smallest units of matter that retain the properties of that element.

Elements are represented on the periodic table, and each element has a unique atomic number that corresponds to the number of protons in its atoms. This classification into elements is crucial in understanding chemical reactions and the composition of matter, as elements combine to form compounds and molecules.

In contrast to elements, compounds are substances formed when two or more elements are chemically bonded together, while molecules refer specifically to groups of atoms bonded together, which can include multiple atoms of the same or different elements. Atoms are indeed essential as the building blocks of elements, but they cannot stand alone as the simplest form of matter in terms of classification within chemical science.