Yes, Helium is lighter than air. Helium is element #2, whereas oxygen is #8. Oxygen has an atomic mass of 16, and helium has a mass of 4, so helium is 4 times lighter than air. So helium balloons float.
| Identifier (URI) | Rank |
|---|---|
| dbkwik:resource/uoSJZP-IuMzlT_vD79us5A== | 5.88129e-14 |