| 1. | Lothar Meyer plotted the physical properties against the atomic number and obtained a periodically repeated pattern. |
| 2. | French geologist, Chancourtois made a cylindrical table of elements to display the periodic recurrence of properties. |
| 3. | Mendeleev realized that some of the elements did not fit in with his scheme of classification if the order of atomic number was strictly followed. |
| 4. | Seaborg was awarded the Nobel Prize in chemistry for his work and Element 101 has been named Seaborgium (Sg) in his honour. |