How to Write 氕 (piē) — Meaning “Protium”

Imagine a small 'pie' slice (the stroke 丿) floating in the air (the radical 气). This helps you recall that 氕 represents protium, the lightest isotope of hydrogen, like a tiny piece of gas.

First write the radical 气 in the standard 4-stroke order (丿, 一, 一, 乚), then add a final left-falling stroke 丿. A common mistake is writing the last stroke as a dot or hook; it must be a clear diagonal line that slightly crosses under the second horizontal stroke of 气.

气 is the gas radical itself and is a standalone character meaning 'air' or 'gas', while 氕 adds a single stroke to become a chemical term for protium. 氖 (nǎi) also uses the gas radical but has the component 乃 inside, making it more complex; 氕 is simpler with only one stroke inside.

氕 is a specialized scientific character used mainly in chemistry to denote the protium isotope of hydrogen (¹H). It appears in terms like 氕气 (protium gas) and 氕原子 (protium atom), but it is rarely used outside academic or technical discussions about isotopes.

Common words containing 氕 include: 氕气 (piē qì) — Protium gas; 氕原子 (piē yuán zi) — Protium atom; 氕核 (piē hé) — Protium nucleus.