2 - Elements and CompoundsOnline version Chapter 9, Lesson 2 - Elements and Compounds. Click the "Show Clue" button to read the hint and answer on the line. by Naneth Burquez 1 Dimitri Mendeleev classified elements in this chart. Hints 1 It is a chart that shows the elements in order of increasing atomic number. 2 It is arranged in vertical columns, called groups or families, and horizontal rows, called periods. 3 The elements found here belong to one of three groups: metals, nonmetals, and metalloids (according to their properties).