How to Write 卟 (bǔ) — Meaning “porphyrin (chemical term)”

Imagine a mouth (口) saying "boo!" like a ghost, and the 卜 part looks like a small cross that reminds you of the chemical ring structure of porphyrin. You can also think of the sound "bǔ" as "boo" and link it to the English word "porphyrin" which starts with "p" but sounds similar. This visual and phonetic trick helps connect the character to its chemical usage.

卟 has 5 strokes: first write the left radical 口 (3 strokes: vertical, horizontal fold, horizontal), then write the right component 卜 (2 strokes: left-falling diagonal, then a dot on the upper right). A common mistake is making the 卜 too large or misplacing the dot too low; keep the 口 about half the width and the 卜 compact. Also note that the diagonal stroke of 卜 should slant left, not be a straight vertical.

Unlike 口 (mouth, a simple square), 卟 has an extra component on the right. Compared to 古 (old, which has 十 above 口), 卟 uses 卜 on the right instead of on top. Visually, 古 looks like a cross on top of a box, while 卟 has a diagonal line and dot beside the box. In meaning, 口 and 古 are common everyday characters, whereas 卟 is a rare chemical term only used in scientific contexts.

卟 is almost never used alone; it appears only in specialized chemistry terms such as 卟啉 (porphyrin) and 卟吩 (porphine). These words describe complex organic compounds found in hemoglobin and chlorophyll. There are no cultural or everyday uses for 卟, so language learners will only encounter it in advanced biochemistry or medical texts.

Common words containing 卟 include: 卟吩 (bǔ fēn) — porphine; 卟啉 (bǔ lín) — porphyrin; 卟吩环 (bǔ fēn huán) — porphine ring.