What is the simplest form of any matter called?

The simplest form of any matter is referred to as an element. An element is a pure substance that cannot be broken down into simpler substances by chemical means. Each element is made up of atoms, which are the smallest units retaining the properties of that element. There are 118 known elements, each represented on the periodic table with a unique atomic number corresponding to the number of protons in its nucleus.

Molecules, on the other hand, consist of two or more atoms bonded together. Compounds are specific types of molecules made up of atoms from different elements. Therefore, while molecules and compounds relate to combinations of elements, the term element itself specifically describes the fundamental building blocks of matter that remain unchanged in their simplest form.