The periodic table can be filled by tabulating elements in order of increasing atomic number. This method was first devised by Russian chemist Dmitri Ivanovitch Mendeleev in 1869 and has been used in physical and chemical science since.
The arrangement of the elements in the table groups them together according to the likeness in their physical and chemical characteristics. A row of chemical elements is called a period, while a column of chemical elements is called a group. Elements are grouped into even larger categories called blocks. The four blocks of the periodic table are designated s, p, d and f. Elements in close proximity to one another in the periodic table generally have similar physical and chemical properties.
The atomic number, by which the elements of the periodic table are ordered, is a whole number indicating the number of protons in the nuclei of the atoms of that element and, consequently, the number of electrons in orbit around these nuclei. Chemical and physical properties of an element are completely dependent on the structure of the atoms, making the periodic table an effective way to organize and predict the properties of all known elements and even make guesses regarding the properties of yet undiscovered elements.