氧
yǎng · HSK 7
oxygen (chemistry)
气 gas radical + 羊 (sheep, yáng) for the sound yǎng = the gas oxygen
The 气 component marks gases (also in 氢 hydrogen, 氮 nitrogen). The 羊 sheep part is purely phonetic, lending the yǎng sound. So: a gas whose name sounds like yáng.
氧 — gas radical 气 + sheep 羊 (phonetic)
氧 is a modern semantic-phonetic compound coined in the 19th century to name the element oxygen. The 气 radical signals 'gas/vapor,' while 羊 (yáng) supplies the sound. It is not an ancient pictograph but part of a systematic set of element names like 氢 (hydrogen) and 氮 (nitrogen).