Potassium (K), an alkali metal, and magnesium (Mg), an alkaline earth metal, both combine readily with bromine (Br), a halogen. What compound will each element (K and Mg) most likely form with bromine?

Question

Potassium (K), an alkali metal, and magnesium (Mg), an alkaline earth metal, both combine readily with bromine (Br), a halogen.  What compound will each element (K and Mg) most likely form with bromine?

GPT-4o mini · Answer

When potassium (K) combines with bromine (Br), it forms potassium bromide (KBr). Potassium is an alkali metal that typically forms a +1 cation (K⁺), while bromine forms a -1 anion (Br⁻). The reaction can be represented as:

\[ 2 K (s) + Br_2 (g) \rightarrow 2 KBr (s) \]

On the other hand, when magnesium (Mg) combines with bromine, it forms magnesium bromide (MgBr₂). Magnesium is an alkaline earth metal that typically forms a +2 cation (Mg²⁺), and bromine still forms a -1 anion (Br⁻). Since two bromide ions are needed to balance the charge of one magnesium ion, the formula is:

\[ Mg (s) + Br_2 (g) \rightarrow MgBr_2 (s) \]

In summary, potassium will most likely form potassium bromide (KBr) and magnesium will most likely form magnesium bromide (MgBr₂) when they react with bromine.