Densest Elemental Gases
Key Findings
About This Dataset
Densest Elemental GasesRadon is the densest elemental gas at 9.73 g/L, roughly eight times denser than air and more than 100 times denser than hydrogen. As a rule, gas density tracks atomic mass: the heavy noble gases radon, xenon (5.89) and krypton (3.75) top the list, while the lightest gases, hydrogen (0.090) and helium, sit at the bottom. The reactive halogens chlorine (3.2) and fluorine (1.70) slot in among the noble gases according to their molecular weight. Everyday air, dominated by nitrogen (1.25) and oxygen (1.43), falls in the middle of this range. The more than hundredfold spread between radon and hydrogen explains why hydrogen and helium balloons float upward, while dense radon tends to collect in basements and poorly ventilated spaces.
Data Insights
Numbers, trends & sources behind this chart
Methodology & source
- Data source
- Royal Society of Chemistry
- Coverage
- 10 entities · 10 observations
- Measure
- Gas Density at STP (g/L)
- Last updated
- 7 July 2026
- Compiled by
- The ANYSTAT team, from the source above
- Values are shown as reported by the source. Nothing is rescaled, rebased or converted — the only changes are thousand separators and decimals shown to two places.
- Entities are ranked highest-first on their value.
Data Sources & References
All external sources cited in this dataset
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