What is the basic unit of a chemical element?

The basic unit of a chemical element is an atom. An atom represents the smallest unit of matter that retains the properties of an element. Each atom consists of a nucleus, containing protons and neutrons, surrounded by electrons that orbit the nucleus. The specific arrangement and number of these subatomic particles determine the chemical identity of the element and its behavior in reactions.

Molecules, on the other hand, are formed when two or more atoms bond together, which can include atoms of the same or different elements. Compounds are specific types of molecules made from at least two different elements. Ions are charged particles that occur when an atom gains or loses electrons, resulting in a positive or negative charge, but they are not considered basic units of a chemical element themselves. Therefore, the concept of the atom as the fundamental building block of elements is essential in understanding the structure of matter and the basis of chemical reactions.