Meaning-based. The second half also names a property of the element. From 硅素 in japanese
History of the character
Every form found in the sources, from the first missionary chemistry books of the 1850s to the current
standards. Hover a dot for the source. Simplified 硅, traditional 硅, Taiwan 矽xì.
1868玻精格物入門 Géwù Rùmén, W. A. P. Martin (丁韙良), Tongwen College
1870玻化學初階 Huàxué Chūjiē, John G. Kerr (嘉約翰) & Hé Liǎorán (何瞭然)
1871夕里西恩金石識別 Jīnshí Shíbié, D. J. MacGowan (瑪高溫) & Huà Héngfāng (華蘅芳)
1871矽化學鑑原 Huàxué Jiànyuán, Xú Shòu (徐壽) & John Fryer (傅蘭雅), Jiangnan Arsenal
1933矽xī化學命名原則 Principles of Chemical Nomenclature, Zhèng Zhènwén (鄭貞文), National Institute for Compilation and Translationadopted over 硅, which came from the Japanese 珪素
1955硅guī無機化合物名詞審查 Inorganic terms review, Chemical terms committee, PRCchanged on the mainland because 矽 xī was a homophone of 硒 selenium and 錫 tin
today矽xì臺灣正體(國家教育研究院) Current Taiwan standard, National Academy for Educational Research, Taiwan
Homophones
No other element shares this syllable.
Elsewhere
Japaneseケイ素Korean규소Vietnamesesilic
Western name from Latin silex, silicis, “flint”. Compare all