The periodic table is a tabular array of the chemical elements organised by atomic number, from the element with the lowest atomic number, hydrogen, to the element with the highest atomic number, oganesson. The atomic number of an element is the number of protons in the nucleus of an atom of that element. Hydrogen has 1 proton, and oganesson has 118. In this lesson we look at the structure of the periodic table and where the different types of elements occur on the periodic table.