Timeline of chemical element discoveries Modern discoveries Modern discoveries

| Z | Element_ | Observed_or_predicted | Isolated_widely_known | Observer | First_isolator | Notes_ |
|---|---|---|---|---|---|---|
| 31 | Gallium | 1875 |  | P. E. L. de Boisbaudran | P. E. L. de Boisbaudran | Boisbaudran observed on a pyrenea blende sample some emission lines corresponding to the eka-aluminium that was predicted by Mendeleev in 1871 and subsequently isolated the element by electrolysis. |
| 70 | Ytterbium | 1878 | 1907 | J.C.G. de Marignac | G. Urbain | On October 22, 1878, Marignac reported splitting terbia into two new earths, terbia proper and ytterbia. |
| 67 | Holmium | 1878 |  | M. Delafontaine |  | Delafontaine found it in samarskite and next year, Per Teodor Cleve split Marignac`s erbia into erbia proper and two new elements, thulium and holmium. |
| 69 | Thulium | 1879 | 1879 | T. Cleve | T. Cleve | Cleve split Marignac`s erbia into erbia proper and two new elements, thulium and holmium. |