Why are transition metals typically denser than s-block elements?

Transition metals are typically denser than s-block elements due to their smaller atomic radii and higher atomic masses.

Transition metals, which are found in the d-block of the periodic table, are generally denser than the s-block elements because of their atomic structure. The atomic radius of transition metals is smaller compared to s-block elements. This is due to the fact that the additional electrons in transition metals are added to the inner d-orbitals, not the outermost shell. This results in a smaller atomic size because the outermost electrons are closer to the nucleus and are more strongly attracted to it, causing the atomic radius to decrease.

In addition to this, transition metals have higher atomic masses. The atomic mass is determined by the total number of protons and neutrons in an atom. Transition metals have more protons and neutrons compared to s-block elements, leading to a greater atomic mass.

When considering density, it is important to remember that it is defined as mass per unit volume. Given that transition metals have a higher atomic mass and a smaller atomic radius, they occupy less space (volume) for a greater amount of matter (mass). This results in a higher density compared to s-block elements, which have a larger atomic radius and a lower atomic mass.

Furthermore, transition metals have a higher packing efficiency due to their close-packed structures. This means that their atoms can pack closely together, leaving less empty space between them. This also contributes to their higher density.

In summary, the higher density of transition metals compared to s-block elements can be attributed to their smaller atomic radii, higher atomic masses, and higher packing efficiency. These factors result in a greater amount of matter occupying less space, leading to a higher density.