Timeline of chemical element discoveries Modern discoveries Modern discoveries

| Z | Element_ | Observed_or_predicted | Isolated_widely_known | Observer | First_isolator | Notes_ |
|---|---|---|---|---|---|---|
| 34 | Selenium | 1817 | 1817 | J. Berzelius and G. Gahn | J. Berzelius and G. Gahn | While working with lead they discovered a substance that they thought was tellurium, but realized after more investigation that it is different. |
| 14 | Silicon | 1824 | 1824 | J. Berzelius | J. Berzelius | Humphry Davy thought in 1800 that silica was an element, not a compound, and in 1808 suggested the present name. In 1811 Louis-Joseph Gay-Lussac and Louis-Jacques Thénard probably prepared impure silicon, but Berzelius is credited with the discovery for obtaining the pure element in 1824. |