What are the groups on the periodic table and how do they relate to the periodic period of elements?

The groups on the Periodic Table are vertical columns that contain elements with similar chemical properties. Elements in the same group have the same number of valence electrons, which determines their reactivity and chemical behavior. The periodic period of elements refers to the horizontal rows on the periodic table, which indicate the number of electron shells an element has. Elements in the same period have the same number of electron shells, but elements in the same group can be in different periods.