The correct increasing order of density for alkali metals is: — s Block Elements Chemistry Question

💡 Solution & Explanation

Density generally increases from Li to Cs due to the mass increasing faster than the volume. However, Potassium ($K$) is an exception; it is lighter than Sodium ($Na$) due to an abnormal increase in atomic volume caused by the presence of vacant 3d orbitals. Thus, $Li < K < Na < Rb < Cs$.