炭素
たんそ · tanso · JLPT N1 · noun
carbon
炭 — mountain 山 + cliff 厂 + fire 火
炭 depicts charcoal produced by burning wood from the mountainside. The top combines 山 (mountain) and 厂 (cliff/slope), suggesting the hillside source of timber, while 火 (fire) below shows the burning process. The original meaning was charcoal, later extended to coal and carbon.
素 — silk 糸 + sheng 𠂹 (hanging threads)
Originally depicted raw, undyed silk hanging to dry, with the silk radical 糸 below and strands above. From this came the meaning 'plain, unadorned, white,' then extended to 'basic element' or 'plain/simple' in general. The 'vegetarian' sense developed later from the idea of plain, unembellished food.