Densest Elemental Gases

About This Dataset

This chart ranks the elements that exist as gases by their density at standard temperature and pressure, in grams per litre. Radon, a heavy radioactive noble gas, is by far the densest elemental gas.

✨ AI Insight

Radon 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.

Source: Royal Society of Chemistry

Key Findings

Auto-computed highlights from this dataset

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Radon leads with 10 in All Time.

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Average value in All Time: 3 · median: 2.

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Gap in All Time: Radon is 108.2× larger than Hydrogen.