Carbon weighs 12.011 g/mol, and water (H₂O) adds up to 18.015 g/mol: add the atomic weights of every atom in the formula.
| No. | Symbol | Element | Atomic weight (g/mol) |
|---|---|---|---|
| 1 | H | Hydrogen | 1.0080 |
| 2 | He | Helium | 4.0026 |
| 3 | Li | Lithium | 6.94 |
| 4 | Be | Beryllium | 9.0122 |
| 5 | B | Boron | 10.81 |
| 6 | C | Carbon | 12.011 |
| 7 | N | Nitrogen | 14.007 |
| 8 | O | Oxygen | 15.999 |
| 9 | F | Fluorine | 18.998 |
| 10 | Ne | Neon | 20.180 |
| 11 | Na | Sodium | 22.990 |
| 12 | Mg | Magnesium | 24.305 |
| 13 | Al | Aluminum | 26.982 |
| 14 | Si | Silicon | 28.085 |
| 15 | P | Phosphorus | 30.974 |
| 16 | S | Sulfur | 32.06 |
| 17 | Cl | Chlorine | 35.45 |
| 18 | Ar | Argon | 39.95 |
| 19 | K | Potassium | 39.098 |
| 20 | Ca | Calcium | 40.078 |
| 21 | Sc | Scandium | 44.956 |
| 22 | Ti | Titanium | 47.867 |
| 23 | V | Vanadium | 50.942 |
| 24 | Cr | Chromium | 51.996 |
| 25 | Mn | Manganese | 54.938 |
| 26 | Fe | Iron | 55.845 |
| 27 | Co | Cobalt | 58.933 |
| 28 | Ni | Nickel | 58.693 |
| 29 | Cu | Copper | 63.546 |
| 30 | Zn | Zinc | 65.38 |
| 31 | Ga | Gallium | 69.723 |
| 32 | Ge | Germanium | 72.630 |
| 33 | As | Arsenic | 74.922 |
| 34 | Se | Selenium | 78.971 |
| 35 | Br | Bromine | 79.904 |
| 36 | Kr | Krypton | 83.798 |
| 37 | Rb | Rubidium | 85.468 |
| 38 | Sr | Strontium | 87.62 |
| 39 | Y | Yttrium | 88.906 |
| 40 | Zr | Zirconium | 91.222 |
| 41 | Nb | Niobium | 92.906 |
| 42 | Mo | Molybdenum | 95.95 |
| 43 | Tc | Technetium | [97] |
| 44 | Ru | Ruthenium | 101.07 |
| 45 | Rh | Rhodium | 102.91 |
| 46 | Pd | Palladium | 106.42 |
| 47 | Ag | Silver | 107.87 |
| 48 | Cd | Cadmium | 112.41 |
| 49 | In | Indium | 114.82 |
| 50 | Sn | Tin | 118.71 |
| 51 | Sb | Antimony | 121.76 |
| 52 | Te | Tellurium | 127.60 |
| 53 | I | Iodine | 126.90 |
| 54 | Xe | Xenon | 131.29 |
| 55 | Cs | Cesium | 132.91 |
| 56 | Ba | Barium | 137.33 |
| 57 | La | Lanthanum | 138.91 |
| 58 | Ce | Cerium | 140.12 |
| 59 | Pr | Praseodymium | 140.91 |
| 60 | Nd | Neodymium | 144.24 |
| 61 | Pm | Promethium | [145] |
| 62 | Sm | Samarium | 150.36 |
| 63 | Eu | Europium | 151.96 |
| 64 | Gd | Gadolinium | 157.25 |
| 65 | Tb | Terbium | 158.93 |
| 66 | Dy | Dysprosium | 162.50 |
| 67 | Ho | Holmium | 164.93 |
| 68 | Er | Erbium | 167.26 |
| 69 | Tm | Thulium | 168.93 |
| 70 | Yb | Ytterbium | 173.05 |
| 71 | Lu | Lutetium | 174.97 |
| 72 | Hf | Hafnium | 178.49 |
| 73 | Ta | Tantalum | 180.95 |
| 74 | W | Tungsten | 183.84 |
| 75 | Re | Rhenium | 186.21 |
| 76 | Os | Osmium | 190.23 |
| 77 | Ir | Iridium | 192.22 |
| 78 | Pt | Platinum | 195.08 |
| 79 | Au | Gold | 196.97 |
| 80 | Hg | Mercury | 200.59 |
| 81 | Tl | Thallium | 204.38 |
| 82 | Pb | Lead | 207.2 |
| 83 | Bi | Bismuth | 208.98 |
| 84 | Po | Polonium | [209] |
| 85 | At | Astatine | [210] |
| 86 | Rn | Radon | [222] |
| 87 | Fr | Francium | [223] |
| 88 | Ra | Radium | [226] |
| 89 | Ac | Actinium | [227] |
| 90 | Th | Thorium | 232.04 |
| 91 | Pa | Protactinium | 231.04 |
| 92 | U | Uranium | 238.03 |
| 93 | Np | Neptunium | [237] |
| 94 | Pu | Plutonium | [244] |
| 95 | Am | Americium | [243] |
| 96 | Cm | Curium | [247] |
| 97 | Bk | Berkelium | [247] |
| 98 | Cf | Californium | [251] |
| 99 | Es | Einsteinium | [252] |
| 100 | Fm | Fermium | [257] |
| 101 | Md | Mendelevium | [258] |
| 102 | No | Nobelium | [259] |
| 103 | Lr | Lawrencium | [262] |
| 104 | Rf | Rutherfordium | [267] |
| 105 | Db | Dubnium | [268] |
| 106 | Sg | Seaborgium | [269] |
| 107 | Bh | Bohrium | [270] |
| 108 | Hs | Hassium | [269] |
| 109 | Mt | Meitnerium | [278] |
| 110 | Ds | Darmstadtium | [281] |
| 111 | Rg | Roentgenium | [282] |
| 112 | Cn | Copernicium | [285] |
| 113 | Nh | Nihonium | [286] |
| 114 | Fl | Flerovium | [289] |
| 115 | Mc | Moscovium | [290] |
| 116 | Lv | Livermorium | [293] |
| 117 | Ts | Tennessine | [294] |
| 118 | Og | Oganesson | [294] |
How it is computed
Values are the IUPAC abridged standard atomic weights. The atomic weight in unified atomic mass units equals the molar mass in grams per mole. Elements with no stable isotope show, in brackets, the mass number of their longest-lived isotope.
FAQ
How do I get the molar mass of a compound?+
Multiply each element's atomic weight by its number of atoms in the formula and add them up. For H₂O: 2 × hydrogen + 1 × oxygen.
What do the numbers in brackets mean?+
Those elements have no stable isotope and no standard atomic weight; the bracketed number is the mass number of their longest-lived isotope.