WHAT do the period rows tell you?

Answer 1

The period rows in the Periodic Table indicate the energy levels of the electrons in an atom. Each row corresponds to a principal quantum number, with elements in the same row having their outermost electrons in the same energy level. As you move from left to right across a period, the number of protons and electrons increases, leading to changes in properties such as electronegativity and atomic size. Thus, period rows help to organize elements by their electron configurations and chemical behaviors.