What does it mean if 2 elements are in the same period on the periodic table?

If two elements are in the same period on the Periodic Table, it means they have the same number of electron shells or energy levels in their atomic structure. As you move across a period from left to right, the elements typically exhibit increasing atomic numbers and varying chemical properties, as they gain additional electrons and protons. This arrangement reflects trends in reactivity, ionization energy, and electronegativity among the elements in that period.