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Exact Masses of the Elements and Isotopic Abundances

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The following data was collected from a compilation of data from the CRC Handbook and other references. If any errors or corrections are notes please advise us and we will make the corrections. Based on the Carbon 12 Standard.

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Name Symbol Mass Abund.
Aluminum Al(27) 26.981541 100.00
Antimony Sb(121) 120.903824 57.30
Antimony Sb(123) 122.904222 42.70
Argon Ar(36) 35.967546 0.34
Argon Ar(38) 37.962732 0.063
Argon Ar(40) 39.962383 99.60
Arsenic As(75) 74.921596 100.00
Barium Ba(130) 129.906277 0.11
Barium Ba(132) 131.905042 0.10
Barium Ba(134) 133.904490 2.42
Barium Ba(135) 134.905668 6.59
Barium Ba(136) 135.904556 7.85
Barium Ba(137) 136.905816 11.23
Barium Ba(138) 137.905236 71.70
Beryllium Be(9) 9.012183 100.00
Bismuth Bi(209) 208.980388 100.00
Boron B(10) 10.012938 19.80
Boron B(11) 11.009305 80.20
Bromine Br(79) 78.918336 50.69
Bromine Br(81) 80.916290 49.31
Calcium Ca(40) 39.962591 96.95
Calcium Ca(42) 41.958622 0.65
Calcium Ca(43) 42.958770 0.14
Calcium Ca(44) 43.955485 2.086
Calcium Ca(46) 45.953689 0.004
Calcium Ca(48) 47.952532 0.19
Cadmium Cd(106) 105.906461 1.25
Cadmium Cd(108) 107.904186 0.89
Cadmium Cd(110) 109.903007 12.49
Cadmium Cd(111) 110.904182 12.80
Cadmium Cd(112) 111.902761 24.13
Cadmium Cd(113) 112.904401 12.22
Cadmium Cd(114) 113.903361 28.73
Cadmium Cd(116) 115.904758 7.49
Carbon C(12) 12.000000 98.90
Carbon C(13) 13.003355 1.10
Cerium Ce(136) 135.907140 0.19
Cerium Ce(138) 137.905996 0.25
Cerium Ce(140) 139.905442 88.48
Cerium Ce(142) 141.909249 11.08
Cesium Cs(133) 132.905433 100.00
Chlorine Cl(35) 34.968853 75.77
Chlorine Cl(37) 36.965903 24.23
Chromium Cr(50) 49.946046 4.35
Chromium Cr(52) 51.940510 83.79
Chromium Cr(53) 52.940651 9.50
Chromium Cr(54) 53.938882 2.36
Cobalt Co(59) 58.933198 100.00
Copper Cu(63) 62.929599 69.17
Dysprosium Cu(65) 64.927792 30.83
Dysprosium Dy(156) 155.924287 0.060
Dysprosium Dy(158) 157.924412 0.10
Dysprosium Dy(160) 159.925203 2.34
Dysprosium Dy(161) 160.926939 18.90
Dysprosium Dy(162) 161.926805 25.50
Dysprosium Dy(163) 162.928737 24.90
Dysprosium Dy(164) 163.929183 28.20
Erbium Er(162) 161.928787 0.14
Erbium Er(164) 163.929211 1.61
Erbium Er(166) 165.930305 33.60
Erbium Er(167) 166.932061 22.95
Erbium Er(168) 167.932383 26.80
Erbium Er(170) 169.935476 14.90
Europium Eu(151) 150.919860 47.80
Europium Eu(153) 152.921243 52.20
Fluorine F(19) 18.998403 100.00
Gallium Ga(69) 68.925581 60.10
Gallium Ga(71) 70.924701 39.90
Gadolinium Gd(152) 151.919803 0.200
Gadolinium Gd(154) 153.920876 2.18
Gadolinium Gd(155) 154.822629 14.80
Gadolinium Gd(156) 155.922130 20.47
Gadolinium Gd(157) 156.923967 15.65
Gadolinium Gd(158) 157.924111 24.84
Gadolinium Gd(160) 159.927061 21.86
Germanium Ge(70) 69.924250 20.50
Germanium Ge(72) 71.922080 27.40
Germanium Ge(73) 72.923464 7.80
Germanium Ge(74) 73.921179 36.50
Germanium Ge(76) 75.921403 7.80
Gold Au(197) 196.966560 100.00
Hafnium Hf(174) 173.940065 0.16
Hafnium Hf(176) 175.941420 5.20
Hafnium Hf(177) 176.943233 18.60
Hafnium Hf(178) 177.943710 27.10
Hafnium Hf(179) 178.945827 13.74
Hafnium Hf(180) 179.946561 35.20
Helium He(3) 3.016029 .0001
Helium He(4) 4.002603 100.00
Holmium Ho(165) 164.930332 100.00
Hydrogen H(1) 1.007825 99.99
Hydrogen H(2) 2.014102 0.015
Indium In(113) 112.904056 4.30
Indium In(115) 114.903875 95.70
Iodine I(127) 126.904477 100.00
Iridium Ir(191) 190.960603 37.30
Iridium Ir(193) 192.962942 62.70
Iron Fe(54) 53.939612 5.80
Iron Fe(56) 55.934939 91.72
Iron Fe(57) 56.935396 2.20
Iron Fe(58) 57.933278 0.28
Krypton Kr(78) 77.920397 0.35
Krypton Kr(80) 79.916375 2.25
Krypton Kr(82) 81.913483 11.60
Krypton Kr(83) 82.914134 11.50
Krypton Kr(84) 83.911506 57.00
Krypton Kr(86) 85.910614 17.30
Lanthanum La(138) 137.907114 0.09
Lanthanum La(139) 138.906355 99.91
Lead Pb(204) 203.973037 1.40
Lead Pb(206) 205.974455 24.10
Lead Pb(207) 206.975885 22.10
Lead Pb(208) 207.976641 52.40
Lithium Li(6) 6.015123 7.42
Lithium Li(7) 7.016005 92.58
Lutetium Lu(175) 174.940785 97.40
Lutetium Lu(176) 175.942694 2.60
Magnesium Mg(24) 23.985045 78.90
Magnesium Mg(25) 24.985839 10.00
Magnesium Mg(26) 25.982595 11.10
Manganese Mn(55) 54.938046 100.00
Mercury Hg(196) 195.965812 0.15
Mercury Hg(198) 197.966760 10.10
Mercury Hg(199) 198.968269 17.00
Mercury Hg(200) 199.968316 23.10
Mercury Hg(201) 200.970293 13.20
Mercury Hg(202) 201.970632 29.65
Mercury Hg(204) 203.973481 6.80
Molybdenum Mo(92) 91.906809 14.84
Molybdenum Mo(94) 93.905086 9.25
Molybdenum Mo(95) 94.905838 15.92
Molybdenum Mo(96) 95.904676 16.68
Molybdenum Mo(97) 96.906018 9.55
Molybdenum Mo(98) 97.905405 24.13
Molybdenum Mo(100) 99.907473 9.63
Neodymium Nd(142) 141.907731 27.13
Neodymium Nd(143) 142.909823 12.18
Neodymium Nd(144) 143.910096 23.80
Neodymium Nd(145) 144.912582 8.30
Neodymium Nd(146) 145.913126 17.19
Neodymium Nd(148) 147.916901 5.76
Neodymium Nd(150) 149.920900 5.64
Neon Ne(20) 19.992439 90.60
Neon Ne(21) 20.993845 0.26
Neon Ne(22) 21.991384 9.20
Nickel Ni(58) 57.935347 68.27
Nickel Ni(60) 59.930789 26.10
Nickel Ni(61) 60.931059 1.13
Nickel Ni(62) 61.928346 3.59
Nickel Ni(64) 63.927968 0.91
Niobium Nb(93) 92.906378 100.00
Nitrogen N(14) 14.003074 99.63
Nitrogen N(15) 15.000109 0.37
Osmium Os(184) 183.952514 0.02
Osmium Os(186) 185.953852 1.58
Osmium Os(187) 186.955762 1.60
Osmium Os(188) 187.955850 13.30
Osmium Os(189) 188.958156 16.10
Osmium Os(190) 189.958455 26.40
Osmium Os(192) 191.961487 41.00
Oxygen O(16) 15.994915 99.76
Oxygen O(17) 16.999131 0.038
Oxygen O(18) 17.999159 0.20
Palladium Pd(102) 101.905609 1.02
Palladium Pd(104) 103.904026 11.14
Palladium Pd(105) 104.905075 22.33
Palladium Pd(106) 105.903475 27.33
Palladium Pd(108) 107.903894 26.46
Palladium Pd(110) 109.905169 11.72
Phosphorus P(31) 30.973763 100.00
Platinum Pt(190) 189.959937 0.010
Platinum Pt(192) 191.961049 0.79
Platinum Pt(194) 193.962679 32.90
Platinum Pt(195) 194.964785 33.80
Platinum Pt(196) 195.964947 25.30
Platinum Pt(198) 197.967879 7.20
Potassium K(39) 38.963708 93.20
Potassium K(40) 39.963999 0.012
Potassium K(41) 40.961825 6.73
Praseodymium Pr(141) 140.907657 100.00
Rhenium Re(185) 184.952977 37.40
Rhenium Re(187) 186.955765 62.60
Rhodium Rh(103) 102.905503 100.00
Rubidium Rb(85) 84.911800 72.17
Rubidium Rb(87) 86.909184 27.84
Ruthenium Ru(96) 95.907596 5.52
Ruthenium Ru(98) 97.905287 1.88
Ruthenium Ru(99) 98.905937 12.70
Ruthenium Ru(100) 99.904218 12.60
Ruthenium Ru(101) 100.905581 17.00
Ruthenium Ru(102) 101.904348 31.60
Ruthenium Ru(104) 103.905422 18.70
Samarium Sm(144) 143.912009 3.10
Samarium Sm(147) 146.914907 15.00
Samarium Sm(148) 147.914832 11.30
Samarium Sm(149) 148.917193 13.80
Samarium Sm(150) 149.917285 7.40
Samarium Sm(152) 151.919741 26.70
Samarium Sm(154) 153.922218 22.70
Scandium Sc(45) 44.955914 100.00
Selenium Se(74) 73.922477 0.90
Selenium Se(76) 75.919207 9.00
Selenium Se(77) 76.919908 7.60
Selenium Se(78) 77.917304 23.50
Selenium Se(80) 79.916521 49.60
Selenium Se(82) 81.916709 9.40
Silicon Si(28) 27.976928 92.23
Silicon Si(29) 28.976496 4.67
Silicon Si(30) 29.973772 3.10
Silver Ag(107) 106.905095 51.84
Silver Ag(109) 108.904754 48.16
Sodium Na(23) 22.989770 100.00
Strontium Sr(84) 83.913428 0.56
Strontium Sr(86) 85.909273 9.86
Strontium Sr(87) 86.908902 7.00
Strontium Sr(88) 87.905625 82.58
Sulfur S(32) 31.972072 95.02
Sulfur S(33) 32.971459 0.75
Sulfur S(34) 33.967868 4.21
Sulfur S(36) 35.967079 0.020
Tantalum Ta(180) 179.947489 0.012
Tantalum Ta(181) 180.948014 99.99
Tellurium Te(120) 119.904021 0.096
Tellurium Te(122) 121.903055 2.60
Tellurium Te(123) 122.904278 0.91
Tellurium Te(124) 123.902825 4.82
Tellurium Te(125) 124.904435 7.14
Tellurium Te(126) 125.903310 18.95
Tellurium Te(128) 127.904464 31.69
Tellurium Te(130) 129.906229 33.80
Terbium Tb(159) 158.925350 100.00
Thallium Tl(203) 202.972336 29.52
Thallium Tl(205) 204.974410 70.48
Thorium Th(232) 232.038054 100.00
Thulium Tm(169) 168.934225 100.00
Tin Sn(112) 111.904826 0.97
Tin Sn(114) 113.902784 0.65
Tin Sn(115) 114.903348 0.36
Tin Sn(116) 115.901744 14.70
Tin Sn(117) 116.902954 7.70
Tin Sn(118) 117.901607 24.30
Tin Sn(119) 118.903310 8.60
Tin Sn(120) 119.902199 32.40
Tin Sn(122) 121.903440 4.60
Tin Sn(124) 123.905271 5.60
Titanium Ti(46) 45.952633 8.00
Titanium Ti(47) 46.951765 7.30
Titanium Ti(48) 47.947947 73.80
Titanium Ti(49) 48.947871 5.50
Titanium Ti(50) 49.944786 5.40
Tungsten W(180) 179.946727 0.13
Tungsten W(182) 181.948225 26.30
Tungsten W(183) 182.950245 14.30
Tungsten W(184) 183.950953 30.67
Tungsten W(186) 185.954377 28.60
Uranium U(234) 234.040947 0.006
Uranium U(235) 235.043925 0.72
Uranium U(238) 238.050786 99.27
Vanadium V(50) 49.947161 0.25
Vanadium V(51) 50.943963 99.75
Xenon Xe(124) 123.905894 0.10
Xenon X(126) 125.904281 0.09
Xenon Xe(128) 127.903531 1.91
Xenon Xe(129) 128.904780 26.40
Xenon Xe(130) 129.903510 4.10
Xenon Xe(131) 130.905076 21.20
Xenon Xe(132) 131.904148 26.90
Xenon Xe(134) 133.905395 10.40
Xenon Xe(136) 135.907219 8.90
Ytterbium Yb(168) 167.933908 0.13
Ytterbium Yb(170) 169.934774 3.05
Ytterbium Yb(171) 170.936338 14.30
Ytterbium Yb(172) 171.936393 21.90
Ytterbium Yb(173) 172.938222 16.12
Ytterbium Yb(174) 173.938873 31.80
Ytterbium Yb(176) 175.942576 12.70
Yttrium Y(89) 88.905856 100.00
Zinc Zn(64) 63.929145 48.60
Zinc Zn(66) 65.926035 27.90
Zinc Zn(67) 66.927129 4.10
Zinc Zn(68) 67.924846 18.80
Zinc Zn(70) 69.925325 0.60
Zirconium Zr(90) 89.904708 51.45
Zirconium Zr(91) 90.905644 11.27
Zirconium Zr(92) 91.905039 17.17
Zirconium Zr(94) 93.906319 17.33
Zirconium Zr(96) 95.908272 2.78

Authors not responsible for errors, omissions or inaccuracy of the above data. Please notify us of any errors or corrections in the above data.