How many periods, which reflect the number of electron shells in individual atoms, is the periodic table divided into?

Explanation

The periodic table is a system that organizes the chemical elements by the number of protons in the nucleus and the number of electrons in the outer electron shells (orbitals). These two properties play a crucial role in the chemical properties of each element, and correspondingly, there is a relationship between an element's chemistry and its position in the periodic table. The system is depicted as a chart divided into groups (columns), periods (rows), and blocks.