According to atomic theory, what is all matter composed of?

According to atomic theory, all matter is composed of atoms. Atoms are the basic building blocks of matter and consist of a nucleus containing protons and neutrons, surrounded by electrons. This understanding is fundamental in chemistry and physics, as it describes the smallest units of an element that retain its chemical properties. Atoms combine to form molecules, which then make up larger structures and materials.

Molecules are indeed composed of atoms, but they do not encompass all types of matter on their own since not all matter exists as molecules. Ions are charged atoms or molecules and are specific cases of atoms that have gained or lost electrons, but they also do not represent all matter. Electrons, while crucial components of atoms, are just one part of the atomic structure and do not qualify as the building blocks of matter on their own.

The concept of atomic theory emphasizes that it is the atoms themselves that serve as the fundamental units of matter, shaping the universe's diverse array of substances and forming the basis for chemical reactions and interactions.