Timeline of chemical element discoveries Modern discoveries Modern discoveries

| Z | Element_ | Observed_or_predicted | Isolated_widely_known | Observer | First_isolator | Notes_ |
|---|---|---|---|---|---|---|
| 49 | Indium | 1863 | 1867 | F. Reich and T. Richter | T. Richter | Reich and Richter First identified it in sphalerite by its bright indigo-blue spectroscopic emission line. Richter isolated the metal several years later. |
| 2 | Helium | 1868 | 1895 | P. Janssen and N. Lockyer | W. Ramsay, T. Cleve, and N. Langlet | Janssen and Lockyer observed independently a yellow line in the solar spectrum that did not match any other element. , Years later, Ramsay, Cleve, and Langlet observed independently the element trapped in cleveite about the same time. |
|  |  | 1869 |  | D. I. Mendeleev |  | Mendeleev arranges the 63 elements known at that time into the first modern periodic table and correctly predicts several others. |