铝

Metal radical on the left — side form of 金, five strokes preserving the canopy and dots of the gold-and-ore picture. Marks 铝 as a metallic element, like every element-name coined in late-19th-century chemistry: 铁 iron, 铜 copper, 银 silver, 钢 steel. Radical does the meaning work; right side picks the sound.

Right side 吕 supplies the sound directly — same lǚ with no shift. Originally 吕 pictured a string of vertebrae or paired musical pitches; here it serves purely as phonetic. The character 铝 itself is a modern coinage — when Mendeleev's table reached Chinese chemistry, translators slotted lǚ alongside 钅 to spell aluminium, matching the European 'al-' opening.