Timeline of chemical element discoveries Modern discoveries Modern discoveries

| Z | Element_ | Observed_or_predicted | Isolated_widely_known | Observer | First_isolator | Notes_ |
|---|---|---|---|---|---|---|
| 65 | Terbium | 1842 | 1842 | G. Mosander | G. Mosander | In 1842 Mosander split yttria into two more earths, erbia and terbia |
| 44 | Ruthenium | 1807 | 1844 | J. Sniadecki | J. Sniadecki | Sniadecki isolated the element in 1807, but his work was not ratified. Gottfried Wilhelm Osann thought that he found three new metals in Russian platinum samples, and in 1844 Karl Karlovich Klaus confirmed that there was a new element. Klaus is usually recognized as the discoverer of the element. |