1H2He3Li4Be5B6C7N8O9F10Ne11Na12Mg13Al14Si15P16S17Cl18Ar19K20Ca21Sc22Ti23V24Cr25Mn26Fe27Co28Ni29Cu30Zn31Ga32Ge33As34Se35Br36Kr37Rb38Sr39Y40Zr41Nb42Mo43Tc44Ru45Rh46Pd47Ag48Cd49In50Sn51Sb52Te53I54Xe55Cs56BaLa*Lanthanides57La58Ce59Pr60Nd61Pm62Sm63Eu64Gd65Tb66Dy67Ho68Er69Tm70Yb71Lu72Hf73Ta74W75Re76Os77Ir78Pt79Au80Hg81Tl82Pb83Bi84Po85At86Rn87Fr88RaAc*Actinides89Ac90Th91Pa92U93Np94Pu95Am96Cm97Bk98Cf99Es100Fm101Md102No103Lr104Rf105Db106Sg107Bh108Hs109Mt110Ds111Rg112Cn113Nh114Fl115Mc116Lv117Ts118Og
HomeScalesStandard atomic weight

Standard atomic weight

Standard atomic weight as a dimensionless arithmetic mean of the relative masses of all isotopes of an element, weighted by their frequency on earth.

ElementStandard atomic weight
1HHydrogen1.008 ±2·10-4 [1.007 … 1.008]
2HeHelium4.002 ±2·10-6
3LiLithium6.94 ±0.06 [6.938 … 6.997]
4BeBeryllium9.012 ±5·10-7
5BBoron10.81 ±0.02 [10.8 … 10.82]
6CCarbon12.01 ±0.002 [12 … 12.01]
7NNitrogen14 ±0.001 [14 … 14]
8OOxygen15.99 ±0.001 [15.99 … 15.99]
9FFluorine18.99 ±5·10-9
10NeNeon20.17 ±6·10-4
11NaSodium22.98 ±2·10-8
12MgMagnesium24.3 ±0.002 [24.3 … 24.3]
13AlAluminum26.98 ±3·10-7
14SiSilicon28.08 ±0.001 [28.08 … 28.08]
15PPhosphorus30.97 ±5·10-9
16SSulfur32.06 ±0.02 [32.05 … 32.07]
17ClChlorine35.45 ±0.01 [35.44 … 35.45]
18ArArgon39.95 ±0.16 [39.79 … 39.96]
19KPotassium39.09 ±1·10-4
20CaCalcium40.07 ±0.004
21ScScandium44.95 ±4·10-6
22TiTitanium47.86 ±0.001
23VVanadium50.94 ±1·10-4
24CrChromium51.99 ±6·10-4
25MnManganese54.93 ±2·10-6
26FeIron55.84 ±0.002
27CoCobalt58.93 ±3·10-6
28NiNickel58.69 ±4·10-4
29CuCopper63.54 ±0.003
30ZnZinc65.38 ±0.02
31GaGallium69.72 ±0.001
32GeGermanium72.63 ±0.008
33AsArsenic74.92 ±6·10-6
34SeSelenium78.97 ±0.008
35BrBromine79.9 ±0.003 [79.9 … 79.9]
36KrKrypton83.79 ±0.002
37RbRubidium85.46 ±3·10-4
38SrStrontium87.62 ±0.01
39YYttrium88.9 ±2·10-6
40ZrZirconium91.22 ±0.002
41NbNiobium92.9 ±1·10-5
42MoMolybdenum95.95 ±0.01
44RuRuthenium101 ±0.02
45RhRhodium102.9 ±2·10-5
46PdPalladium106.4 ±0.01
47AgSilver107.8 ±2·10-4
48CdCadmium112.4 ±0.004
49InIndium114.8 ±0.001
50SnTin118.7 ±0.007
51SbAntimony121.7 ±0.001
52TeTellurium127.6 ±0.03
53IIodine126.9 ±3·10-5
54XeXenon131.2 ±0.006
55CsCaesium132.9 ±5.999·10-8
56BaBarium137.3 ±0.007
57LaLanthanum138.9 ±7·10-5
58CeCerium140.1 ±0.001
59PrPraseodymium140.9 ±1·10-5
60NdNeodymium144.2 ±0.003
62SmSamarium150.3 ±0.02
63EuEuropium151.9 ±0.001
64GdGadolinium157.2 ±0.03
65TbTerbium158.9 ±7·10-6
66DyDysprosium162.5 ±0.001
67HoHolmium164.9 ±5·10-6
68ErErbium167.2 ±0.003
69TmThulium168.9 ±5·10-6
70YbYtterbium173 ±0.01
71LuLutetium174.9 ±1·10-4
72HfHafnium178.4 ±0.006
73TaTantalum180.9 ±2·10-5
74WTungsten183.8 ±0.01
75ReRhenium186.2 ±0.001
76OsOsmium190.2 ±0.03
77IrIridium192.2 ±0.002
78PtPlatinum195 ±0.009
79AuGold196.9 ±4·10-6
80HgMercury200.5 ±0.003
81TlThallium204.3 ±0.01 [204.3 … 204.3]
82PbLead207.2 ±1.1 [206.1 … 207.9]
83BiBismuth208.9 ±1·10-5
90ThThorium232 ±4·10-4
91PaProtactinium231 ±1·10-5
92UUranium238 ±3·10-5