Final answer:
In the periodic table, the elements arranged in vertical columns are called groups or families. These groups, numbered 1 to 18, contain elements with similar chemical properties. Horizontal rows are called periods, indicating elements that share the same level of valence electron energy.
Step-by-step explanation:
In the periodic table, elements in a line that goes up and down are referred to as groups or families. These are the vertical columns numbered 1 to 18, starting from the leftmost side to the rightmost side of the table. Each group contains elements with similar chemical behaviors, mainly because they have the same number of valence electrons.
The periodic table also features seven horizontal rows called periods, which represent elements with the same principal energy levels for their valence electrons. Periods are numbered from 1 at the top to 7 at the bottom. Interestingly, the elements in period 1 only include hydrogen and helium, whereas periods 6 and 7 have many more elements due to the inclusion of the lanthanides and actinides.
Groups on the periodic table also have some common names for certain columns, for instance, the alkali metals in Group 1 and the noble gases in Group 18. These designations are based on characteristic properties shared by the elements within the respective groups.