The electron configuration of argon differs from those of chlorine and potassium by one electron each. Compare the reactivity of these three elements, and relate them to their electron configurations.

Understanding the electron configuration of an element is crucial for predicting its chemical behavior. Electron configuration refers to the distribution of electrons in an element's atomic orbitals. For instance, argon, with its electron configuration of \[1s^2 2s^2 2p^6 3s^2 3p^6\], has a completely filled outer shell, which means all of its orbitals in the highest energy level are fully occupied. This full outer shell is often referred to as a 'noble gas configuration,' noted for its stability.

In contrast, chlorine \[1s^2 2s^2 2p^6 3s^2 3p^5\] and potassium \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^1\] differ—one electron short in the case of chlorine and one extraneous electron in the case of potassium from that stable noble gas configuration. It is this battle to either reach or revert to a full shell that plays a critical role in the reactivity of these elements.

The reactivity of an element is determined by how easily it can lose or gain electrons, which in turn is influenced by its electron configuration. In more detail, chlorine is a single electron shy of a full shell, making it highly reactive, as it seeks to attract an electron to fill this gap. It's like a puzzle missing one piece: chlorine is eager to find that missing piece and complete the picture.

Conversely, potassium has an extra electron that it can readily give up, aiming to revert back to the stable configuration of argon. Potassium is like a tower with an unstable top block—it readily topples that block to become more stable. This give-and-take of electrons amongst atoms is the basis for the formation of chemical bonds and the wide variety of reactions they can undergo. In summary, elements that are one or two electrons away from a full shell can be expected to be highly reactive in their pursuit of electron configuration stability.

Chemical stability is directly linked to how resistant an element is to changing its electron configuration. Argon exemplifies this stability, as it possesses that proverbial 'full outer shell,' which means it has little tendency to react with other elements. It's like a satisfied diner at the end of a hearty meal—no further desire to eat or move.

This stability makes argon, and other noble gases, typically unreactive or inert. The full valence shell signifies a state of minimum energy, so there's no driving force for noble gases to engage in chemical reactions by gaining or losing electrons. In essence, elements with a full valence electron shell like argon are chemical wallflowers, unlikely to interact with the more dynamic elements pursuing the stability that comes with a full electron configuration.