Isotope				Relative Atomic Mass		Isotopic   Composition	Standard Atomic Weight	Notes
14	Si	28	27.976 926 534 65(44)	0.922 23(19)	[28.084, 28.086]
		29	28.976 494 664 90(52)	0.046 85(8)
		30	29.973 770 136(23)	0.030 92(11)
34	Se	74	73.922 475 934(15)	0.0089(4)	78.971(8)	r
		76	75.919 213 704(17)	0.0937(29)
		77	76.919 914 154(67)	0.0763(16)
		78	77.917 309 28(20)	0.2377(28)
		80	79.916 5218(13)	0.4961(41)
		82	81.916 6995(15)	0.0873(22)