Chemical reactivity refers to how an element behaves during a chemical reaction. This behavior is directly tied to the number of valence electrons. Elements strive to achieve the most stable electron arrangement possible, typically through gaining, losing, or sharing valence electrons. In the periodic table, elements placed in the same group share similar reactivity levels due to their identical valence electron configurations. For example:
- Alkali metals (group 1) are eager to lose their single valence electron to attain a stable electron configuration. Consequently, they react intensely with water and other substances.
- Halogens (group 17) are just as reactive, but for a slightly different reason. They seek to gain one electron to complete their valence shell, making them quick to form compounds with metals, like in the formation of salts.
Understanding reactivity based on valence electrons helps anticipate how elements might interact in new or existing chemical reactions.