Mendeleev's periodic table doesn't look a whole lot like the modern periodic table, but it uses a similar format. The elements are grouped in order of increasing atomic weight (we use atomic number now) in a way where elements with common properties appear together, in the same columns. You'll see this type of chart in textbooks and schools all over the world, but it's not the only way to group the elements. There are circular tables, helical tables, three-dimensional tables, and many more. The Chemogenesis Web Book offers a sampling of different types of periodic tables. Note that the tables are still periodic. The elements are categorized according to trends in their properties.