Reactivity Trend in Alkaline Earth Metals with Halogens

The reactivity trend of alkaline earth metals with halogens has been widely studied and understood. When heated, all the alkaline earth metals react directly with halogens to form their corresponding halides with a general formula MX2. One notable exception is that sodium chloride, potassium chloride, and rubidium chloride form non-hydrated chlorides.

The reactivity of alkaline earth metals with halogens increases in the following order: lithium to caesium. This trend can be observed when reacting these metals with a particular halogen. The resulting halides are ionic in nature, crystalline solids, and exhibit high melting and boiling points. However, lithium halides deviate from this trend due to their covalent nature.

The alkali metal halides, except for lithium halides, are good conductors of electricity when fused or dissolved in water. They are also used as a means of preparing the corresponding alkali metals. On the other hand, lithium halides are sparingly soluble in water and exhibit low melting points due to their covalent nature.

The general reaction between an alkaline earth metal and a halogen can be represented as follows: MX + X2 → 2MX. The large atomic size of the alkali metals and their tendency to lose one electron from their valence shell make them highly reactive. This reactivity is also exhibited by all the alkaline earth metals, which react with air, water, hydrogen, halogens, and other non-metals.

In conclusion, the reactivity trend in alkaline earth metals with halogens shows a steady increase from lithium to caesium. The resulting halides are ionic in nature and exhibit high melting and boiling points, except for lithium halides which have covalent properties.

Reactivity trend in alkaline earth