What defines elements that typically share similar properties in the periodic table?

Elements that are located in the same columns, or groups, of the periodic table typically share similar properties because they have the same number of valence electrons. This arrangement leads to similar chemical behaviors and reactivities. For instance, all alkali metals are found in the first column and exhibit similar characteristics like high reactivity with water and a tendency to lose one electron to form positive ions. Thus, the periodic table's columnar structure effectively categorizes elements with comparable traits, making option B the correct choice.

In contrast, elements in the same periods do not necessarily share similar properties; they can be quite different. Atomic mass can vary widely across a group, making that option misleading. Lastly, while many elements in the periodic table are metals, not all are, so identifying a characteristic shared solely by metals does not define a broader grouping of elements.