Timeline of chemical element discoveries Modern discoveries Modern discoveries

| Z | Element_ | Observed_or_predicted | Isolated_widely_known | Observer | First_isolator | Notes_ |
|---|---|---|---|---|---|---|
| 10 | Neon | 1898 | 1898 | W. Ramsay and W. Travers | W. Ramsay and W. Travers | In June 1898 Ramsay separated a new noble gas from liquid argon by difference in boiling point. |
| 54 | Xenon | 1898 | 1898 | W. Ramsay and W. Travers | W. Ramsay and W. Travers | On July 12, 1898 Ramsay separated a third noble gas within three weeks, from liquid argon by difference in boiling point. |
| 84 | Polonium | 1898 | 1902 | P. and M. Curie | W. Marckwald | In an experiment done on July 13, 1898, the Curies noted an increased radioactivity in the uranium obtained from pitchblende, which they ascribed to an unknown element. |