What does atomic theory state about matter?

Atomic theory posits that all matter is composed of atoms, which are the fundamental building blocks of all substances. This concept emerged in the early 19th century, primarily credited to scientists like John Dalton, who proposed that atoms are indivisible particles that combine in various ways to form all the different materials we encounter.

The idea emphasizes that no matter what the form of matter—solid, liquid, or gas—it can always be traced back to these tiny, discrete units known as atoms. Atoms themselves consist of even smaller particles (protons, neutrons, and electrons), but the core principle of atomic theory maintains that atoms are the basic unit of matter. Hence, understanding that everything around us, from the air we breathe to the complex compounds in our bodies, is ultimately composed of atoms is central to chemistry.

In contrast, while molecules are made of atoms, not all matter is made up of molecules, as some elements exist as individual atoms in nature, like noble gases. Additionally, compounds are specific types of molecules formed from two or more different atoms bonded together, thus not all matter consists solely of compounds. Lastly, the notion that all matter is stable and unchanging contradicts atomic theory, which recognizes that atoms can undergo reactions and transformations