Question

The transition metals exhibit a ___ density than the alkali and alkaline earth metals.

Answer 1

The physical properties of the 3d metals are closely related to the presence and number of d electrons. These 3d electrons contribute to extensive metallic bonding, which becomes stronger across the rows and peaks in the middle. This explains the corresponding increase in melting point, density, and enthalpy of atomization. Do note that the densities of the transition metals are significantly higher than those of alkali metals and alkaline earth metals.
As compared to transition metals, the alkali and alkaline earth metals are less dense. This is because the metals of the first two groups have higher atomic volume. The transition metals have higher masses than their corresponding alkali and alkaline earth metals. This, combined with the fact that the atomic volume of transition metals is lower than that of the alkali and alkaline earth metals explains the increased density!