| Answer | Crossword Clue |
|---|---|
| BORON | Element with a low atomic number that is not found naturally on Earth |
| lawrencium | The chemical element of atomic number 103, a radioactive metal of the actinide series. Lawrencium does not occur naturally and was first made by bombarding californium with boron nuclei |
| berkelium | The chemical element of atomic number 97, a radioactive metal of the actinide series. Berkelium does not occur naturally and was first made by bombarding americium with helium ions |
| mendelevium | The chemical element of atomic number 101, a radioactive metal of the actinide series. It does not occur naturally and was first made in 1955 by bombarding einsteinium with helium ions |
