National League for Nursing (NLN PAX) Practice Exam

The vertical columns on the periodic table are referred to as groups, which is significant because elements within the same group share similar chemical properties and have the same number of valence electrons. For instance, elements in Group 1 (alkali metals) are highly reactive and have one electron in their outermost shell, leading to similar reactivity patterns. This structural organization helps predict how elements will interact in chemical reactions.

Periods, in contrast, are the horizontal rows of the periodic table and represent the sequence of elements as they increase in atomic number. Ions refer to charged particles that result from the gain or loss of electrons and are not related to the grouping of elements on the periodic table. Metalloids are a category of elements that possess properties of both metals and nonmetals, but they do not define the vertical organization of the table.