Understanding Halogen and Alkali Metal Reactivity Patterns
The halogens reactivity down the group follows a distinct pattern that chemistry students need to understand. All halogens share similar chemical properties due to their electron configuration, with each having seven electrons in their outer shell. This electronic structure explains why does reactivity decrease down group 7 - as atomic size increases down the group, the attraction between the nucleus and outer electrons weakens.
Definition Halogens are Group 7 elements that exist as diatomic molecules (F₂, Cl₂, Br₂, I₂, At₂) and become progressively less reactive down the group.
When examining halogen displacement reactions examples, we see that more reactive halogens will displace less reactive ones from their compounds. For instance, chlorine can displace bromine from sodium bromide solution, producing sodium chloride and bromine. This demonstrates that chlorine is more reactive than bromine. The most reactive halogen in group 7 is fluorine, followed by chlorine, bromine, iodine, and astatine.
Alkali metals and halogens reaction produces ionic compounds called salts. For example, when sodium reacts with bromine, it forms sodium bromide NaBr. The balanced equation is 2Na + Br₂ → 2NaBr. These reactions are typically vigorous due to the high reactivity of both groups.