How to Write 氡 (dōng) — Meaning “radon”

Imagine that in winter (冬), a strange gas (气) fills the air — that gas is radon. This links the shape of 气 (like a cloud) with the season 冬 to mean radon gas, 氡.

First write the radical 气: draw a short left-falling stroke, then a horizontal, a horizontal hook, and a dot. Then add 冬 on the right, with its top part (a left-falling and a combined stroke) and two dots at the bottom. A common mistake is making the hook of 气 too sharp or the right side too wide.

All three share the gas radical 气, but their right parts differ: 氡 has 冬 (winter), 氙 has 山 (mountain), and 氚 has 川 (river). Each represents a different gas: radon, xenon, and tritium, and they are not interchangeable.

氡 appears mostly in scientific and environmental writing about radon gas, such as in reports on indoor air quality or radiation safety. It is not common in daily conversation, but you may see it in news about home testing for radon (测氡) or radon concentration (氡浓度).

Common words containing 氡 include: 氡气 (dōng qì) — radon gas; 测氡 (cè dōng) — radon measurement; 氡浓度 (dōng nóng dù) — radon concentration.