The periodic table is a systematic, tabular arrangement of all known chemical elements organized by increasing atomic number, which is the number of protons in an atom's nucleus

. It is arranged in rows called periods and columns called groups, where elements in the same group share similar chemical properties due to having the same number of electrons in their outer shell

. This organization reveals recurring patterns in element properties, known as the periodic law, allowing scientists to predict the behavior and characteristics of elements based on their position in the table

. The table includes over 100 elements, both naturally occurring and synthetic, and is fundamental to chemistry, physics, and other sciences

. The periodic table was first widely accepted after Dmitri Mendeleev's version in 1869, who used it to predict properties of then-undiscovered elements

. Its modern form reflects advances in atomic theory and quantum mechanics, grouping elements into blocks (s, p, d, f) based on electron configurations

. In summary, the periodic table is a crucial scientific tool that organizes elements to highlight their atomic structure and chemical relationships, facilitating understanding and discovery in science