31.11: The Chemical Elements (Appendix K)
| Element | Symbol | Atomic Number | Atomic Weight 1 | Percentage of Naturally Occurring Elements in the Universe |
|---|---|---|---|---|
| Hydrogen | H | 1 | 1.008 | 75 |
| Helium | He | 2 | 4.003 | 23 |
| Lithium | Li | 3 | 6.94 | 6 × 10 −7 |
| Beryllium | Be | 4 | 9.012 | 1 × 10 −7 |
| Boron | B | 5 | 10.821 | 1 × 10 −7 |
| Carbon | C | 6 | 12.011 | 0.5 |
| Nitrogen | N | 7 | 14.007 | 0.1 |
| Oxygen | O | 8 | 15.999 | 1 |
| Fluorine | F | 9 | 18.998 | 4 × 10 −5 |
| Neon | Ne | 10 | 20.180 | 0.13 |
| Sodium | Na | 11 | 22.990 | 0.002 |
| Magnesium | Mg | 12 | 24.305 | 0.06 |
| Aluminum | Al | 13 | 26.982 | 0.005 |
| Silicon | Si | 14 | 28.085 | 0.07 |
| Phosphorus | P | 15 | 30.974 | 7 × 10 −4 |
| Sulfur | S | 16 | 32.06 | 0.05 |
| Chlorine | Cl | 17 | 35.45 | 1 × 10 −4 |
| Argon | Ar | 18 | 39.948 | 0.02 |
| Potassium | K | 19 | 39.098 | 3 × 10 −4 |
| Calcium | Ca | 20 | 40.078 | 0.007 |
| Scandium | Sc | 21 | 44.956 | 3 × 10 −6 |
| Titanium | Ti | 22 | 47.867 | 3 × 10 −4 |
| Vanadium | V | 23 | 50.942 | 3 × 10 −4 |
| Chromium | Cr | 24 | 51.996 | 0.0015 |
| Manganese | Mn | 25 | 54.938 | 8 × 10 −4 |
| Iron | Fe | 26 | 55.845 | 0.11 |
| Cobalt | Co | 27 | 58.933 | 3 × 10 −4 |
| Nickel | Ni | 28 | 58.693 | 0.006 |
| Copper | Cu | 29 | 63.546 | 6 × 10 −6 |
| Zinc | Zn | 30 | 65.38 | 3 × 10 −5 |
| Gallium | Ga | 31 | 69.723 | 1 × 10 −6 |
| Germanium | Ge | 32 | 72.630 | 2 × 10 −5 |
| Arsenic | As | 33 | 74.922 | 8 × 10 −7 |
| Selenium | Se | 34 | 78.971 | 3 × 10 −6 |
| Bromine | Br | 35 | 79.904 | 7 × 10 −7 |
| Krypton | Kr | 36 | 83.798 | 4 × 10 −6 |
| Rubidium | Rb | 37 | 85.468 | 1 × 10 −6 |
| ’Strontium | Sr | 38 | 87.62 | 4 × 10 −6 |
| Yttrium | Y | 39 | 88.906 | 7 × 10 −7 |
| Zirconium | Zr | 40 | 91.224 | 5 × 10 −6 |
| Niobium | Nb | 41 | 92.906 | 2 × 10 −7 |
| Molybdenum | Mo | 42 | 95.95 | 5 × 10 −7 |
| Technetium | Tc | 43 | (98) | — |
| Ruthenium | Ru | 44 | 101.07 | 4 × 10 −7 |
| Rhodium | Rh | 45 | 102.906 | 6 × 10 −8 |
| Palladium | Pd | 46 | 106.42 | 2 × 10 −7 |
| Silver | Ag | 47 | 107.868 | 6 × 10 −8 |
| Cadmium | Cd | 48 | 112.414 | 2 × 10 −7 |
| Indium | In | 49 | 114.818 | 3 × 10 −8 |
| Tin | Sn | 50 | 118.710 | 4 × 10 −7 |
| Antimony | Sb | 51 | 121.760 | 4 × 10 −8 |
| Tellurium | Te | 52 | 127.60 | 9 × 10 −7 |
| Iodine | I | 53 | 126.904 | 1 × 10 −7 |
| Xenon | Xe | 54 | 131.293 | 1 × 10 −6 |
| Cesium | Cs | 55 | 132.905 | 8 × 10 −8 |
| Barium | Ba | 56 | 137.327 | 1 × 10 −6 |
| Lanthanum | La | 57 | 138.905 | 2 × 10 −7 |
| Cerium | Ce | 58 | 140.116 | 1 × 10 −6 |
| Praseodymium | Pr | 59 | 140.907 | 2 × 10 −7 |
| Neodymium | Nd | 60 | 144.242 | 1 × 10 −6 |
| Promethium | Pm | 61 | (145) | — |
| Samarium | Sm | 62 | 150.36 | 5 × 10 −7 |
| Europium | Eu | 63 | 151.964 | 5 × 10 −8 |
| Gadolinium | Gd | 64 | 157.25 | 2 × 10 −7 |
| Terbium | Tb | 65 | 158.925 | 5 × 10 −8 |
| Dysprosium | Dy | 66 | 162.500 | 2 × 10 −7 |
| Holmium | Ho | 67 | 164.930 | 5 × 10 −8 |
| Erbium | Er | 68 | 167.259 | 2 × 10 −7 |
| Thulium | Tm | 69 | 168.934 | 1 × 10 −8 |
| Ytterbium | Yb | 70 | 173.054 | 2 × 10 −7 |
| Lutetium | Lu | 71 | 174.967 | 1 × 10 −8 |
| Hafnium | Hf | 72 | 178.49 | 7 × 10 −8 |
| Tantalum | Ta | 73 | 180.948 | 8 × 10 −9 |
| Tungsten | W | 74 | 183.84 | 5 × 10 −8 |
| Rhenium | Re | 75 | 186.207 | 2 × 10 −8 |
| Osmium | Os | 76 | 190.23 | 3 × 10 −7 |
| Iridium | Ir | 77 | 192.217 | 2 × 10 −7 |
| Platinum | Pt | 78 | 195.084 | 5 × 10 −7 |
| Gold | Au | 79 | 196.967 | 6 × 10 −8 |
| Mercury | Hg | 80 | 200.592 | 1 × 10 −7 |
| Thallium | TI | 81 | 204.38 | 5 × 10 −8 |
| Lead | Pb | 82 | 207.2 | 1 × 10 −6 |
| Bismuth | Bi | 83 | 208.980 | 7 × 10 −8 |
| Polonium | Po | 84 | (209) | — |
| Astatine | At | 85 | (210) | — |
| Radon | Rn | 86 | (222) | — |
| Francium | Fr | 87 | (223) | — |
| Radium | Ra | 88 | (226) | — |
| Actinium | Ac | 89 | (227) | — |
| Thorium | Th | 90 | 232.038 | 4 × 10 −8 |
| Protactinium | Pa | 91 | 231.036 | — |
| Uranium | U | 92 | 238.029 | 2 × 10 −8 |
| Neptunium | Np | 93 | (237) | — |
| Plutonium | Pu | 94 | (244) | — |
| Americium | Am | 95 | (243) | — |
| Curium | Cm | 96 | (247) | — |
| Berkelium | Bk | 97 | (247) | — |
| Californium | Cf | 98 | (251) | — |
| Einsteinium | Es | 99 | (252) | — |
| Fermium | Fm | 100 | (257) | — |
| Mendelevium | Md | 101 | (258) | — |
| Nobelium | No | 102 | (259) | — |
| Lawrencium | Lr | 103 | (262) | — |
| Rutherfordium | Rf | 104 | (267) | — |
| Dubnium | Db | 105 | (268) | — |
| Seaborgium | Sg | 106 | (271) | — |
| Bohrium | Bh | 107 | (272) | — |
| Hassium | Hs | 108 | (270) | — |
| Meitnerium | Mt | 109 | (276) | — |
| Darmstadtium | Ds | 110 | (281) | — |
| Roentgenium | Rg | 111 | (280) | — |
| Copernicium | Cn | 112 | (285) | — |
| Nihonium | Nh | 113 | (284) | — |
| Flerovium | Fl | 114 | (289) | — |
| Moskovium | Mc | 115 | (288) | — |
| Livermorium | Lv | 116 | (293) | — |
| Tennessine | Ts | 117 | (294) | — |
| Oganesson | Og | 118 | (294) | — |
Note: Some of the newest elements near the bottom of the table have suggested names that are still under review, and those names are not yet listed here. For example, Tennessine is suggested for element 117, after the state where the Oak Ridge National Laboratory is located.
Footnotes
1 Where mean atomic weights have not been well determined, the atomic mass numbers of the most stable isotopes are given in parentheses.