Final answer:
Atomic size, metallic character, and atomic density are properties that increase down the periodic table due to the addition of energy levels and the increased distance of valence electrons from the nucleus.
Step-by-step explanation:
When examining the periodic table, we notice certain properties demonstrating specific trends as you move down the column (group) of the table. One particular property that increases down the periodic table is the atomic size or atomic radius. The reason behind this increment is the addition of principal energy levels which places valence electrons physically farther away from the nucleus with each subsequent element in a group.
Another property that increases is the metallic character. Metallic properties like conductivity and malleability are associated with the ease of removing electrons, which becomes easier as electrons in atoms lower down in a group are farther from the nucleus. Thus, elements exhibit a stronger metallic character as you progress down a group.
We also observe that atomic density generally increases down a group. This occurs because as the atomic size grows, the mass of the atom typically increases as well, leading to a higher density. It's important to note that while these trends are generally consistent, there can be exceptions based on the presence of partially filled or fully filled subshells.