Z | Symbol | Name | Ar°(E) 2021: Table 1, columns 4, 5 |
Type |
Abridged columns 7, 8 |
g, m, r | m.s.i. | Year changed |
---|---|---|---|---|---|---|---|---|
1 | H | hydrogen | [1.00784, 1.00811] | 2 | 1.0080±0.0002 | m | 2009[1] | |
2 | He | helium | 4.002602±0.000002 | 1 | 4.0026±0.0001 | g, r | 1983[2] | |
3 | Li | lithium | [6.938, 6.997] | 2 | 6.94±0.06 | m | 2009[3] | |
4 | Be | beryllium | 9.0121831±0.0000005 | 1 | 9.0122±0.0001 | 2013[4] | ||
5 | B | boron | [10.806, 10.821] | 2 | 10.81±0.02 | m | 2009[5] | |
6 | C | carbon | [12.0096, 12.0116] | 2 | 12.011±0.002 | 2009[6] | ||
7 | N | nitrogen | [14.00643, 14.00728] | 2 | 14.007±0.001 | m | 2009[7] | |
8 | O | oxygen | [15.99903, 15.99977] | 2 | 15.999±0.001 | m | 2009[8] | |
9 | F | fluorine | 18.998403162±0.000000005 | 1 | 18.998±0.001 | 2021[9] | ||
10 | Ne | neon | 20.1797±0.0006 | 1 | 20.180±0.001 | g, m | 1985[10] | |
11 | Na | sodium | 22.98976928±0.00000002 | 1 | 22.990±0.001 | 2005[11] | ||
12 | Mg | magnesium | [24.304, 24.307] | 2 | 24.305±0.002 | 2011[12] | ||
13 | Al | aluminium | 26.9815384±0.0000003 | 1 | 26.982±0.001 | 2017[13] | ||
14 | Si | silicon | [28.084, 28.086] | 2 | 28.085±0.001 | 2009[14] | ||
15 | P | phosphorus | 30.973761998±0.000000005 | 1 | 30.974±0.001 | 2013[15] | ||
16 | S | sulfur | [32.059, 32.076] | 2 | 32.06±0.02 | 2009[16] | ||
17 | Cl | chlorine | [35.446, 35.457] | 2 | 35.45±0.01 | m | 2009[17] | |
18 | Ar | argon | [39.792, 39.963] | 2 | 39.95±0.16 | 2017[18] | ||
19 | K | potassium | 39.0983±0.0001 | 1 | 39.098±0.001 | 1979[19] | ||
20 | Ca | calcium | 40.078±0.004 | 1 | 40.078±0.004 | g | 1983[20] | |
21 | Sc | scandium | 44.955907±0.000004 | 1 | 44.956±0.001 | 2021[21] | ||
22 | Ti | titanium | 47.867±0.001 | 1 | 47.867±0.001 | 1993[22] | ||
23 | V | vanadium | 50.9415±0.0001 | 1 | 50.942±0.001 | 1977[23] | ||
24 | Cr | chromium | 51.9961±0.0006 | 1 | 51.996±0.001 | 1983[24] | ||
25 | Mn | manganese | 54.938043±0.000002 | 1 | 54.938±0.001 | 2017[25] | ||
26 | Fe | iron | 55.845±0.002 | 1 | 55.845±0.002 | 1993[26] | ||
27 | Co | cobalt | 58.933194±0.000003 | 1 | 58.933±0.001 | 2017[27] | ||
28 | Ni | nickel | 58.6934±0.0004 | 1 | 58.693±0.001 | r | 2007[28] | |
29 | Cu | copper | 63.546±0.003 | 1 | 63.546±0.003 | r | 1969[29] | |
30 | Zn | zinc | 65.38±0.02 | 1 | 65.38±0.02 | r | 2007[30] | |
31 | Ga | gallium | 69.723±0.001 | 1 | 69.723±0.001 | 1987[31] | ||
32 | Ge | germanium | 72.630±0.008 | 1 | 72.630±0.008 | 2009[32] | ||
33 | As | arsenic | 74.921595±0.000006 | 1 | 74.922±0.001 | 2013[33] | ||
34 | Se | selenium | 78.971±0.008 | 1 | 78.971±0.008 | r | 2013[34] | |
35 | Br | bromine | [79.901, 79.907] | 2 | 79.904±0.003 | 2011[35] | ||
36 | Kr | krypton | 83.798±0.002 | 1 | 83.798±0.002 | g, m | 2001[36] | |
37 | Rb | rubidium | 85.4678±0.0003 | 1 | 85.468±0.001 | g | 1969[37] | |
38 | Sr | strontium | 87.62±0.01 | 1 | 87.62±0.01 | g, r | 1969[38] | |
39 | Y | yttrium | 88.905838±0.000002 | 1 | 88.906±0.001 | 2021[39] | ||
40 | Zr | zirconium | 91.222±0.003 | 1 | 91.222±0.003 | g | 2024[40] | |
41 | Nb | niobium | 92.90637±0.00001 | 1 | 92.906±0.001 | 2017[41] | ||
42 | Mo | molybdenum | 95.95±0.01 | 1 | 95.95±0.01 | g | 2013[42] | |
43 | Tc | technetium | - | 3 | [97] | |||
44 | Ru | ruthenium | 101.07±0.02 | 1 | 101.07±0.02 | g | 1983[43] | |
45 | Rh | rhodium | 102.90549±0.00002 | 1 | 102.91±0.01 | 2017[44] | ||
46 | Pd | palladium | 106.42±0.01 | 1 | 106.42±0.01 | g | 1979[45] | |
47 | Ag | silver | 107.8682±0.0002 | 1 | 107.87±0.01 | g | 1985[46] | |
48 | Cd | cadmium | 112.414±0.004 | 1 | 112.41±0.01 | g | 2013[47] | |
49 | In | indium | 114.818±0.001 | 1 | 114.82±0.01 | 2011[48] | ||
50 | Sn | tin | 118.710±0.007 | 1 | 118.71±0.01 | g | 1983[49] | |
51 | Sb | antimony | 121.760±0.001 | 1 | 121.76±0.01 | g | 1993[50] | |
52 | Te | tellurium | 127.60±0.03 | 1 | 127.60±0.03 | g | 1969[51] | |
53 | I | iodine | 126.90447±0.00003 | 1 | 126.90±0.01 | 1985[52] | ||
54 | Xe | xenon | 131.293±0.006 | 1 | 131.29±0.01 | g, m | 1999[53] | |
55 | Cs | caesium | 132.90545196±0.00000006 | 1 | 132.91±0.01 | 2013[54] | ||
56 | Ba | barium | 137.327±0.007 | 1 | 137.33±0.01 | 1985[55] | ||
57 | La | lanthanum | 138.90547±0.00007 | 1 | 138.91±0.01 | g | 2005[56] | |
58 | Ce | cerium | 140.116±0.001 | 1 | 140.12±0.01 | g | 1995[57] | |
59 | Pr | praseodymium | 140.90766±0.00001 | 1 | 140.91±0.01 | 2017[58] | ||
60 | Nd | neodymium | 144.242±0.003 | 1 | 144.24±0.01 | g | 2005[59] | |
61 | Pm | promethium | 3 | [145] | ||||
62 | Sm | samarium | 150.36±0.02 | 1 | 150.36±0.02 | g | 2005[60] | |
63 | Eu | europium | 151.964±0.001 | 1 | 151.96±0.01 | g | 1995[61] | |
64 | Gd | gadolinium | 157.249±0.002 | 1 | 157.25±0.01 | g | 2024[62] | |
65 | Tb | terbium | 158.925354±0.000007 | 1 | 158.93±0.01 | 2021[63] | ||
66 | Dy | dysprosium | 162.500±0.001 | 1 | 162.50±0.01 | g | 2001[64] | |
67 | Ho | holmium | 164.930329±0.000005 | 1 | 164.93±0.01 | 2021[65] | ||
68 | Er | erbium | 167.259±0.003 | 1 | 167.26±0.01 | g | 1999[66] | |
69 | Tm | thulium | 168.934219±0.000005 | 1 | 168.93±0.01 | 2021[67] | ||
70 | Yb | ytterbium | 173.045±0.010 | 1 | 173.05±0.02 | g | 2015[68] | |
71 | Lu | lutetium | 174.96669±0.00005 | 1 | 174.97±0.01 | g | 2024[69] | |
72 | Hf | hafnium | 178.486±0.006 | 1 | 178.49±0.01 | g | 2019[70] | |
73 | Ta | tantalum | 180.94788±0.00002 | 1 | 180.95±0.01 | 2005[71] | ||
74 | W | tungsten | 183.84±0.01 | 1 | 183.84±0.01 | 1991[72] | ||
75 | Re | rhenium | 186.207±0.001 | 1 | 186.21±0.01 | 1973[73] | ||
76 | Os | osmium | 190.23±0.03 | 1 | 190.23±0.03 | g | 1991[74] | |
77 | Ir | iridium | 192.217±0.002 | 1 | 192.22±0.01 | 2017[75] | ||
78 | Pt | platinum | 195.084±0.009 | 1 | 195.08±0.02 | 2005[76] | ||
79 | Au | gold | 196.966570±0.000004 | 1 | 196.97±0.01 | 2017[77] | ||
80 | Hg | mercury | 200.592±0.003 | 1 | 200.59±0.01 | 2011[78] | ||
81 | Tl | thallium | [204.382, 204.385] | 2 | 204.38±0.01 | 2009[79] | ||
82 | Pb | lead | [206.14, 207.94] | 2 | 207.2±1.1 | 2020[80] | ||
83 | Bi | bismuth | 208.98040±0.00001 | 1 | 208.98±0.01 | 2005[81] | ||
84 | Po | polonium | - | 3 | [209] | |||
85 | At | astatine | - | 3 | [210] | |||
86 | Rn | radon | - | 3 | [222] | |||
87 | Fr | francium | - | 3 | [223] | |||
88 | Ra | radium | - | 3 | [226] | |||
89 | Ac | actinium | - | 3 | [227] | |||
90 | Th | thorium | 232.0377±0.0004 | 1 | 232.04±0.01 | g | 2013[82] | |
91 | Pa | protactinium | 231.03588±0.00001 | 1 | 231.04±0.01 | 2017[83] | ||
92 | U | uranium | 238.02891±0.00003 | 1 | 238.03±0.01 | g, m | 1999[84] | |
93 | Np | neptunium | - | 3 | [237] | |||
94 | Pu | plutonium | - | 3 | [244] | |||
95 | Am | americium | - | 3 | [243] | |||
96 | Cm | curium | - | 3 | [247] | |||
97 | Bk | berkelium | - | 3 | [247] | |||
98 | Cf | californium | - | 3 | [251] | |||
99 | Es | einsteinium | - | 3 | [252] | |||
100 | Fm | fermium | - | 3 | [257] | |||
101 | Md | mendelevium | - | 3 | [258] | |||
102 | No | nobelium | - | 3 | [259] | |||
103 | Lr | lawrencium | - | 3 | [266] | |||
104 | Rf | rutherfordium | - | 3 | [267] | |||
105 | Db | dubnium | - | 3 | [268] | |||
106 | Sg | seaborgium | - | 3 | [267] | |||
107 | Bh | bohrium | - | 3 | [270] | |||
108 | Hs | hassium | - | 3 | [271] | |||
109 | Mt | meitnerium | - | 3 | [278] | |||
110 | Ds | darmstadtium | - | 3 | [281] | |||
111 | Rg | roentgenium | - | 3 | [282] | |||
112 | Cn | copernicium | - | 3 | [285] | |||
113 | Nh | nihonium | - | 3 | [286] | |||
114 | Fl | flerovium | - | 3 | [289] | |||
115 | Mc | moscovium | - | 3 | [290] | |||
116 | Lv | livermorium | - | 3 | [293] | |||
117 | Ts | tennessine | - | 3 | [294] | |||
118 | Og | oganesson | - | 3 | [294] | |||
119 | Uue | ununennium | - | |||||
120 | Ubn | unbinilium | - | |||||
121 | Ubu | unbiunium | - | |||||
122 | Ubb | unbibium | - | |||||
124 | Ubq | unbiquadium | - | |||||
126 | Ubh | unbihexium | - |
g | Geological and biological materials are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic weight of the element in such materials and that given in the table may exceed the stated uncertainty. | |||||||
m | Modified isotopic compositions may be found in commercially available material because the material has been subjected to some undisclosed or inadvertent isotopic fractionation. Substantial deviations in atomic weight of the element from that given in the table can occur. | |||||||
r | Range in isotopic composition of normal terrestrial material prevents a more precise standard atomic weight being given; the tabulated value and uncertainty should be applicable to normal material. |