Timeline of chemical element discoveries Modern discoveries Modern discoveries

| Z | Element_ | Observed_or_predicted | Isolated_widely_known | Observer | First_isolator | Notes_ |
|---|---|---|---|---|---|---|
| 19 | Potassium | 1807 | 1807 | H. Davy | H. Davy | Davy discovered it by using electrolysis on potash. |
| 11 | Sodium | 1807 | 1807 | H. Davy | H. Davy | Davy discovered it a few days after potassium, by using electrolysis on sodium hydroxide. |
| 20 | Calcium | 1808 | 1808 | H. Davy | H. Davy | Davy discovered the metal by electrolysis of quicklime. |
| 5 | Boron | 1808 | 1808 | L. Gay-Lussac and L.J. Thénard | H. Davy | On June 21, 1808, Lussac and Thénard announced a new element in sedative salt, Davy announced the isolation of a new substance from boracic acid soon afterwards. |