矽（原子量：280855 3）共有 23 個已知同位素，質量數介於 2244 之間，其中有 3 個是穩定的，其他都具有放射性。天然存在的矽同位素有 5 個，分別是穩定的 28Si、29Si、30Si 和具放射性的 31Si 及 32Si，31Si 及 32Si 在自然界中僅痕量存在，為宇宙射線散裂所產生。其餘同位素都不出現在自然界中，只有在實驗室製造出來過，且半衰期都極短，非常不穩定。 圖表 rowspan222Si rowspan2 styletextalignright 14 rowspan2 styletextalignright 8 rowspan22203611 54 rowspan229 2 ms 68 22Al rowspan20 rowspan2 rowspan2 β p 32 21Mg 23Si styletextalignright 14 styletextalignright 9 2302571 54 423 4 ms β 23Al 32 rowspan224Si rowspan2 styletextalignright 14 rowspan2 styletextalignright 10 rowspan224011535 21 rowspan2140 8 ms β 92 24Al rowspan20 rowspan2 rowspan2 β p 8 23Mg rowspan225Si rowspan2 styletextalignright 14 rowspan2 styletextalignright 11 rowspan225004109 11 rowspan2220 3 ms β 6319 25Al rowspan252 rowspan2 rowspan2 β p 368 24Mg 26Si styletextalignright 14 styletextalignright 12 2599233382 12 2234 13 s β 26Al 0 27Si styletextalignright 14 styletextalignright 13 2698670469 12 416 2 s β 27Al 52 28Si styletextalignright 14 styletextalignright 14 279769265344 6 colspan3 aligncenter 0 092223 19 092205092241 29Si styletextalignright 14 styletextalignright 15 289764946643 6 colspan3 aligncenter 穩定 12 004685 8 004678004692 30Si styletextalignright 14 styletextalignright 16 29973770137 23 colspan3 aligncenter 穩定 0 003092 11 003082003102 31Si styletextalignright 14 styletextalignright 17 3097536320 5 1573 3 min β 31P 32 32Si styletextalignright 14 styletextalignright 18 319741515 3 153 19 y β 32P 0 痕量或天然放射性 33Si styletextalignright 14 styletextalignright 19 329779770 8 618 18 s β 33P 32 34Si styletextalignright 14 styletextalignright 20 339785380 9 277 20 s β 34P 0 rowspan235Si rowspan2 styletextalignright 14 rowspan2 styletextalignright 21 rowspan23498455 4 rowspan2780 120 ms β 9474 35P rowspan272 rowspan2 rowspan2 β n 526 34P rowspan236Si rowspan2 styletextalignright 14 rowspan2 styletextalignright 22 rowspan23598665 8 rowspan2045 6 s β 88 36P rowspan20 rowspan2 rowspan2 β n 12 35P rowspan237Si rowspan2 styletextalignright 14 rowspan2 styletextalignright 23 rowspan23699295 12 rowspan290 60 ms β 83 37P rowspan272 rowspan2 rowspan2 β n 17 36P rowspan238Si rowspan2 styletextalignright 14 rowspan2 styletextalignright 24 rowspan23799552 11 rowspan290 ms 1 µs β n 37P rowspan20 rowspan2 rowspan2 β 38P 39Si styletextalignright 14 styletextalignright 25 3900249 15 475 20 ms β 39P 72 40Si styletextalignright 14 styletextalignright 26 4000608 13 330 10 ms β 40P 0 41Si styletextalignright 14 styletextalignright 27 4101417 32 200 25 ms β 41P 72 42Si styletextalignright 14 styletextalignright 28 4201808 32 13 4 ms β 42P 0 43Si styletextalignright 14 styletextalignright 29 4302612 43 15 ms 260 ns 32 44Si styletextalignright 14 styletextalignright 30 4403147 54 10 ms 0 參考文獻 Isotopic compositions and standard atomic masses from Atomic weights of the elements Review 2000 IUPAC Technical Report Pure Appl Chem Vol 75 No 6 pp 683800 2003 and Atomic Weights Revised 2005 Halflife spin and isomer data selected from these sources Editing notes on this articles talk page Audi Bersillon Blachot Wapstra The Nubase2003 evaluation of nuclear and decay properties Nuc Phys A 729 pp 3128 2003 National Nuclear Data Center Brookhaven National Laboratory Information extracted from the NuDat 21 database retrieved Sept 2005 David R Lide ed Norman E Holden in CRC Handbook of Chemistry and Physics 85th Edition online version CRC Press Boca Raton Florida 2005 Section 11 Table of the Isotopes Si Category 矽