Would you expect strontium (Sr) to be more like potassium (K) or bromine (Br)? Why?
The Correct answer and Explanation is:
Strontium (Sr) would be expected to be more like potassium (K) than bromine (Br). This similarity is rooted in their positions in the periodic table and their elemental properties.
Both strontium and potassium are classified as metals, while bromine is a non-metal. Strontium is located in group 2 (alkaline earth metals) of the periodic table, and potassium is in group 1 (alkali metals). These groups share similar chemical properties due to their electron configurations. Potassium has the electron configuration [Ar] 4s¹, which means it has one valence electron that it readily loses to form a +1 ion (K⁺). Strontium, on the other hand, has the electron configuration [Kr] 5s², indicating that it has two valence electrons and typically forms a +2 ion (Sr²⁺) when it reacts.
Both potassium and strontium are characterized by their metallic luster, malleability, and good electrical conductivity. They also exhibit similar reactivity patterns, especially with water; both react vigorously, producing hydroxides and hydrogen gas. For example, potassium reacts with water to form potassium hydroxide (KOH), while strontium reacts to form strontium hydroxide (Sr(OH)₂).
In contrast, bromine is a halogen, found in group 17, and possesses very different characteristics. It has a tendency to gain electrons, forming negative ions (Br⁻) and is typically less reactive with metals compared to alkali and alkaline earth metals. Bromine is also a diatomic molecule (Br₂) in its elemental form, which differs significantly from the metallic nature of strontium and potassium.
In summary, strontium is more akin to potassium due to their shared properties as metals, similar reactivity patterns, and their tendency to lose electrons to form cations, contrasting sharply with the non-metallic and electron-accepting behavior of bromine.