Why are iron and transition metals used in construction instead of alkali metals?

Iron and transition metals are preferred in construction due to their strength, durability, and resistance to corrosion, making them suitable for structural applications. In contrast, alkali metals are highly reactive, especially with water and air, which limits their practicality in construction. Moreover, alkali metals are typically softer and less stable, making them unsuitable for supporting heavy loads or withstanding environmental stresses. Overall, the properties of iron and transition metals align better with the demands of construction materials.