Transition metals are typically denser than Group 1 metals.

Transition metals, which include elements such as iron, copper, and gold, are characterized by their high densities. This is primarily attributed to their atomic structure. Transition metals possess more protons and neutrons in their nuclei compared to Group 1 metals, leading to a greater atomic mass. Additionally, their electrons are more closely packed, further contributing to their higher density.

In contrast, Group 1 metals, commonly referred to as alkali metals, include elements like lithium, sodium, and potassium. These metals have fewer protons, neutrons, and electrons, resulting in a lower atomic mass and less tightly packed electron configurations, which in turn leads to a lower density.

For instance, the density of iron (a transition metal) is approximately $7.87 \, \text{g/cm}^3$, while sodium (a Group 1 metal) has a density of only $0.97 \, \text{g/cm}^3$. This significant difference illustrates the general trend observed between these two groups of elements.

Moreover, the unique properties of transition metals, including their density, make them particularly valuable in various applications. Their high density and strength render them ideal for construction and manufacturing purposes. Conversely, the lower densities of Group 1 metals limit their utility in these areas; however, they are advantageous in other applications, such as batteries.

In conclusion, the atomic structure of transition metals results in a higher density compared to that of Group 1 metals. This variation in density plays a crucial role in determining the different uses and properties of these metals.