# Molar ionization energies of the elements

These tables list values of molar ionization energies, measured in kJ⋅mol$^{−1}$. This is the energy per mole necessary to remove electrons from gaseous atoms or atomic ions. The first molar ionization energy applies to the neutral atoms. The second, third, etc., molar ionization energy applies to the further removal of an electron from a singly, doubly, etc., charged ion. For ionization energies measured in the unit eV, see Ionization energies of the elements (data page). All data from rutherfordium onwards is predicted.

## 1st–10th ionization energies

| Number | Symbol | Name | 1st | 2nd | 3rd | 4th | 5th | 6th | 7th | 8th | 9th | 10th |
| 1 | H | hydrogen | 1312.0 |
| 2 | He | helium | 2372.3 | 5250.5 |
| 3 | Li | lithium | 520.2 | 7298.1 | 11,815.0 |
| 4 | Be | beryllium | 899.5 | 1757.1 | 14,848.7 | 21,006.6 |
| 5 | B | boron | 800.6 | 2427.1 | 3659.7 | 25,025.8 | 32,826.7 |
| 6 | C | carbon | 1086.5 | 2352.6 | 4620.5 | 6222.7 | 37,831 | 47,277.0 |
| 7 | N | nitrogen | 1402.3 | 2856 | 4578.1 | 7475.0 | 9444.9 | 53,266.6 | 64,360 |
| 8 | O | oxygen | 1313.9 | 3388.3 | 5300.5 | 7469.2 | 10,989.5 | 13,326.5 | 71,330 | 84,078.0 |
| 9 | F | fluorine | 1681.0 | 3374.2 | 6050.4 | 8407.7 | 11,022.7 | 15,164.1 | 17,868 | 92,038.1 | 106,434.3 |
| 10 | Ne | neon | 2080.7 | 3952.3 | 6122 | 9371 | 12,177 | 15,238.90 | 19,999.0 | 23,069.5 | 115,379.5 | 131,432 |
| 11 | Na | sodium | 495.8 | 4562 | 6910.3 | 9543 | 13,354 | 16,613 | 20,117 | 25,496 | 28,932 | 141,362 |
| 12 | Mg | magnesium | 737.7 | 1450.7 | 7732.7 | 10,542.5 | 13,630 | 18,020 | 21,711 | 25,661 | 31,653 | 35,458 |
| 13 | Al | aluminium | 577.5 | 1816.7 | 2744.8 | 11,577 | 14,842 | 18,379 | 23,326 | 27,465 | 31,853 | 38,473 |
| 14 | Si | silicon | 786.5 | 1577.1 | 3231.6 | 4355.5 | 16,091 | 19,805 | 23,780 | 29,287 | 33,878 | 38,726 |
| 15 | P | phosphorus | 1011.8 | 1907 | 2914.1 | 4963.6 | 6273.9 | 21,267 | 25,431 | 29,872 | 35,905 | 40,950 |
| 16 | S | sulfur | 999.6 | 2252 | 3357 | 4556 | 7004.3 | 8495.8 | 27,107 | 31,719 | 36,621 | 43,177 |
| 17 | Cl | chlorine | 1251.2 | 2298 | 3822 | 5158.6 | 6542 | 9362 | 11,018 | 33,604 | 38,600 | 43,961 |
| 18 | Ar | argon | 1520.6 | 2665.8 | 3931 | 5771 | 7238 | 8781 | 11,995 | 13,842 | 40,760 | 46,186 |
| 19 | K | potassium | 418.8 | 3052 | 4420 | 5877 | 7975 | 9590 | 11,343 | 14,944 | 16,963.7 | 48,610 |
| 20 | Ca | calcium | 589.8 | 1145.4 | 4912.4 | 6491 | 8153 | 10,496 | 12,270 | 14,206 | 18,191 | 20,385 |
| 21 | Sc | scandium | 633.1 | 1235.0 | 2388.6 | 7090.6 | 8843 | 10,679 | 13,310 | 15,250 | 17,370 | 21,726 |
| 22 | Ti | titanium | 658.8 | 1309.8 | 2652.5 | 4174.6 | 9581 | 11,533 | 13,590 | 16,440 | 18,530 | 20,833 |
| 23 | V | vanadium | 650.9 | 1414 | 2830 | 4507 | 6298.7 | 12,363 | 14,530 | 16,730 | 19,860 | 22,240 |
| 24 | Cr | chromium | 652.9 | 1590.6 | 2987 | 4743 | 6702 | 8744.9 | 15,455 | 17,820 | 20,190 | 23,580 |
| 25 | Mn | manganese | 717.3 | 1509.0 | 3248 | 4940 | 6990 | 9220 | 11,500 | 18,770 | 21,400 | 23,960 |
| 26 | Fe | iron | 762.5 | 1561.9 | 2957 | 5290 | 7240 | 9560 | 12,060 | 14,580 | 22,540 | 25,290 |
| 27 | Co | cobalt | 760.4 | 1648 | 3232 | 4950 | 7670 | 9840 | 12,440 | 15,230 | 17,959 | 26,570 |
| 28 | Ni | nickel | 737.1 | 1753.0 | 3395 | 5300 | 7339 | 10,400 | 12,800 | 15,600 | 18,600 | 21,670 |
| 29 | Cu | copper | 745.5 | 1957.9 | 3555 | 5536 | 7700 | 9900 | 13,400 | 16,000 | 19,200 | 22,400 |
| 30 | Zn | zinc | 906.4 | 1733.3 | 3833 | 5731 | 7970 | 10,400 | 12,900 | 16,800 | 19,600 | 23,000 |
| 31 | Ga | gallium | 578.8 | 1979.3 | 2963 | 6180 |
| 32 | Ge | germanium | 762 | 1537.5 | 3302.1 | 4411 | 9020 |
| 33 | As | arsenic | 947.0 | 1798 | 2735 | 4837 | 6043 | 12,310 |
| 34 | Se | selenium | 941.0 | 2045 | 2973.7 | 4144 | 6590 | 7880 | 14,990 |
| 35 | Br | bromine | 1139.9 | 2103 | 3470 | 4560 | 5760 | 8550 | 9940 | 18,600 |
| 36 | Kr | krypton | 1350.8 | 2350.4 | 3565 | 5070 | 6240 | 7570 | 10,710 | 12,138 | 22,274 | 25,880 |
| 37 | Rb | rubidium | 403.0 | 2633 | 3860 | 5080 | 6850 | 8140 | 9570 | 13,120 | 14,500 | 26,740 |
| 38 | Sr | strontium | 549.5 | 1064.2 | 4138 | 5500 | 6910 | 8760 | 10,230 | 11,800 | 15,600 | 17,100 |
| 39 | Y | yttrium | 600 | 1180 | 1980 | 5847 | 7430 | 8970 | 11,190 | 12,450 | 14,110 | 18,400 |
| 40 | Zr | zirconium | 640.1 | 1270 | 2218 | 3313 | 7752 | 9500 |
| 41 | Nb | niobium | 652.1 | 1380 | 2416 | 3700 | 4877 | 9847 | 12,100 |
| 42 | Mo | molybdenum | 684.3 | 1560 | 2618 | 4480 | 5257 | 6640.8 | 12,125 | 13,860 | 15,835 | 17,980 |
| 43 | Tc | technetium | 686.9 | 1470 | 2850 |
| 44 | Ru | ruthenium | 710.2 | 1620 | 2747 |
| 45 | Rh | rhodium | 719.7 | 1740 | 2997 |
| 46 | Pd | palladium | 804.4 | 1870 | 3177 |
| 47 | Ag | silver | 731.0 | 2070 | 3361 |
| 48 | Cd | cadmium | 867.8 | 1631.4 | 3616 |
| 49 | In | indium | 558.3 | 1820.7 | 2704 | 5210 |
| 50 | Sn | tin | 708.6 | 1411.8 | 2943.0 | 3930.3 | 7456 |
| 51 | Sb | antimony | 834 | 1594.9 | 2440 | 4260 | 5400 | 10,400 |
| 52 | Te | tellurium | 869.3 | 1790 | 2698 | 3610 | 5668 | 6820 | 13,200 |
| 53 | I | iodine | 1008.4 | 1845.9 | 3180 |
| 54 | Xe | xenon | 1170.4 | 2046.4 | 3099.4 |
| 55 | Cs | caesium | 375.7 | 2234.3 | 3400 |
| 56 | Ba | barium | 502.9 | 965.2 | 3600 |
| 57 | La | lanthanum | 538.1 | 1067 | 1850.3 | 4819 | 5940 |
| 58 | Ce | cerium | 534.4 | 1050 | 1949 | 3547 | 6325 | 7490 |
| 59 | Pr | praseodymium | 527 | 1020 | 2086 | 3761 | 5551 |
| 60 | Nd | neodymium | 533.1 | 1040 | 2130 | 3900 |
| 61 | Pm | promethium | 540 | 1050 | 2150 | 3970 |
| 62 | Sm | samarium | 544.5 | 1070 | 2260 | 3990 |
| 63 | Eu | europium | 547.1 | 1085 | 2404 | 4120 |
| 64 | Gd | gadolinium | 593.4 | 1170 | 1990 | 4250 |
| 65 | Tb | terbium | 565.8 | 1110 | 2114 | 3839 |
| 66 | Dy | dysprosium | 573.0 | 1130 | 2200 | 3990 |
| 67 | Ho | holmium | 581.0 | 1140 | 2204 | 4100 |
| 68 | Er | erbium | 589.3 | 1150 | 2194 | 4120 |
| 69 | Tm | thulium | 596.7 | 1160 | 2285 | 4120 |
| 70 | Yb | ytterbium | 603.4 | 1174.8 | 2417 | 4203 |
| 71 | Lu | lutetium | 523.5 | 1340 | 2022.3 | 4370 | 6445 |
| 72 | Hf | hafnium | 658.5 | 1440 | 2250 | 3216 |
| 73 | Ta | tantalum | 761 | 1500 |
| 74 | W | tungsten | 770 | 1700 |
| 75 | Re | rhenium | 760 | 1260 | 2510 | 3640 |
| 76 | Os | osmium | 840 | 1600 |
| 77 | Ir | iridium | 880 | 1600 |
| 78 | Pt | platinum | 870 | 1791 |
| 79 | Au | gold | 890.1 | 1980 |
| 80 | Hg | mercury | 1007.1 | 1810 | 3300 |
| 81 | Tl | thallium | 589.4 | 1971 | 2878 |
| 82 | Pb | lead | 715.6 | 1450.5 | 3081.5 | 4083 | 6640 |
| 83 | Bi | bismuth | 703 | 1610 | 2466 | 4370 | 5400 | 8520 |
| 84 | Po | polonium | 812.1 |
| 85 | At | astatine | 899.003 |
| 86 | Rn | radon | 1037 |
| 87 | Fr | francium | 393 |
| 88 | Ra | radium | 509.3 | 979.0 |
| 89 | Ac | actinium | 499 | 1170 | 1900 | 4700 |
| 90 | Th | thorium | 587 | 1110 | 1978 | 2780 |
| 91 | Pa | protactinium | 568 | 1128 | 1814 | 2991 |
| 92 | U | uranium | 597.6 | 1420 | 1900 | 3145 |
| 93 | Np | neptunium | 604.5 | 1128 | 1997 | 3242 |
| 94 | Pu | plutonium | 584.7 | 1128 | 2084 | 3338 |
| 95 | Am | americium | 578 | 1158 | 2132 | 3493 |
| 96 | Cm | curium | 581 | 1196 | 2026 | 3550 |
| 97 | Bk | berkelium | 601 | 1186 | 2152 | 3434 |
| 98 | Cf | californium | 608 | 1206 | 2267 | 3599 |
| 99 | Es | einsteinium | 619 | 1216 | 2334 | 3734 |
| 100 | Fm | fermium | 629 | 1225 | 2363 | 3792 |
| 101 | Md | mendelevium | 636 | 1235 | 2470 | 3840 |
| 102 | No | nobelium | 639 | 1254 | 2643 | 3956 |
| 103 | Lr | lawrencium | 479 | 1428 | 2228 | 4910 |
| 104 | Rf | rutherfordium | 580 | 1390 | 2300 | 3080 |
| 105 | Db | dubnium | 665 | 1547 | 2378 | 3299 | 4305 |
| 106 | Sg | seaborgium | 757 | 1733 | 2484 | 3416 | 4562 | 5716 |
| 107 | Bh | bohrium | 740 | 1690 | 2570 | 3600 | 4730 | 5990 | 7230 |
| 108 | Hs | hassium | 730 | 1760 | 2830 | 3640 | 4940 | 6180 | 7540 | 8860 |
| 109 | Mt | meitnerium | 800 | 1820 | 2900 | 3900 | 4900 |
| 110 | Ds | darmstadtium | 960 | 1890 | 3030 | 4000 | 5100 |
| 111 | Rg | roentgenium | 1020 | 2070 | 3080 | 4100 | 5300 |
| 112 | Cn | copernicium | 1155 | 2170 | 3160 | 4200 | 5500 |
| 113 | Nh | nihonium | 707.2 | 2309 | 3020 | 4382 | 5638 |
| 114 | Fl | flerovium | 832.2 | 1600 | 3370 | 4400 | 5850 |
| 115 | Mc | moscovium | 538.3 | 1760 | 2650 | 4680 | 5720 |
| 116 | Lv | livermorium | 663.9 | 1330 | 2850 | 3810 | 6080 |
| 117 | Ts | tennessine | 736.9 | 1435.4 | 2161.9 | 4012.9 | 5076.4 |
| 118 | Og | oganesson | 860.1 | 1560 |
| 119 | Uue | ununennium | 463.1 | 1700 |
| 120 | Ubn | unbinilium | 563.3 | 895– 919 |
| 121 | Ubu | unbiunium | 429.4 | 1110 | 1710 | 4270 |
| 122 | Ubb | unbibium | 545 | 1090 | 1848 | 2520 |

## 11th–20th ionisation energies

| number | symbol | name | 11th | 12th | 13th | 14th | 15th | 16th | 17th | 18th | 19th | 20th |
| 11 | Na | sodium | 159,076 |
| 12 | Mg | magnesium | 169,988 | 189,368 |
| 13 | Al | aluminium | 42,647 | 201,266 | 222,316 |
| 14 | Si | silicon | 45,962 | 50,502 | 235,196 | 257,923 |
| 15 | P | phosphorus | 46,261 | 54,110 | 59,024 | 271,791 | 296,195 |
| 16 | S | sulfur | 48,710 | 54,460 | 62,930 | 68,216 | 311,048 | 337,138 |
| 17 | Cl | chlorine | 51,068 | 57,119 | 63,363 | 72,341 | 78,095 | 352,994 | 380,760 |
| 18 | Ar | argon | 52,002 | 59,653 | 66,199 | 72,918 | 82,473 | 88,576 | 397,605 | 427,066 |
| 19 | K | potassium | 54,490 | 60,730 | 68,950 | 75,900 | 83,080 | 93,400 | 99,710 | 444,880 | 476,063 |
| 20 | Ca | calcium | 57,110 | 63,410 | 70,110 | 78,890 | 86,310 | 94,000 | 104,900 | 111,711 | 494,850 | 527,762 |
| 21 | Sc | scandium | 24,102 | 66,320 | 73,010 | 80,160 | 89,490 | 97,400 | 105,600 | 117,000 | 124,270 | 547,530 |
| 22 | Ti | titanium | 25,575 | 28,125 | 76,015 | 83,280 | 90,880 | 100,700 | 109,100 | 117,800 | 129,900 | 137,530 |
| 23 | V | vanadium | 24,670 | 29,730 | 32,446 | 86,450 | 94,170 | 102,300 | 112,700 | 121,600 | 130,700 | 143,400 |
| 24 | Cr | chromium | 26,130 | 28,750 | 34,230 | 37,066 | 97,510 | 105,800 | 114,300 | 125,300 | 134,700 | 144,300 |
| 25 | Mn | manganese | 27,590 | 30,330 | 33,150 | 38,880 | 41,987 | 109,480 | 118,100 | 127,100 | 138,600 | 148,500 |
| 26 | Fe | iron | 28,000 | 31,920 | 34,830 | 37,840 | 44,100 | 47,206 | 122,200 | 131,000 | 140,500 | 152,600 |
| 27 | Co | cobalt | 29,400 | 32,400 | 36,600 | 39,700 | 42,800 | 49,396 | 52,737 | 134,810 | 145,170 | 154,700 |
| 28 | Ni | nickel | 30,970 | 34,000 | 37,100 | 41,500 | 44,800 | 48,100 | 55,101 | 58,570 | 148,700 | 159,000 |
| 29 | Cu | copper | 25,600 | 35,600 | 38,700 | 42,000 | 46,700 | 50,200 | 53,700 | 61,100 | 64,702 | 163,700 |
| 30 | Zn | zinc | 26,400 | 29,990 | 40,490 | 43,800 | 47,300 | 52,300 | 55,900 | 59,700 | 67,300 | 71,200 |
| 36 | Kr | krypton | 29,700 | 33,800 | 37,700 | 43,100 | 47,500 | 52,200 | 57,100 | 61,800 | 75,800 | 80,400 |
| 38 | Sr | strontium | 31,270 |
| 39 | Y | yttrium | 19,900 | 36,090 |
| 42 | Mo | molybdenum | 20,190 | 22,219 | 26,930 | 29,196 | 52,490 | 55,000 | 61,400 | 67,700 | 74,000 | 80,400 |

## 21st–30th ionisation energies

| number | symbol | name | 21st | 22nd | 23rd | 24th | 25th | 26th | 27th | 28th | 29th | 30th |
| 21 | Sc | scandium | 582,163 |
| 22 | Ti | titanium | 602,930 | 639,294 |
| 23 | V | vanadium | 151,440 | 661,050 | 699,144 |
| 24 | Cr | chromium | 157,700 | 166,090 | 721,870 | 761,733 |
| 25 | Mn | manganese | 158,600 | 172,500 | 181,380 | 785,450 | 827,067 |
| 26 | Fe | iron | 163,000 | 173,600 | 188,100 | 195,200 | 851,800 | 895,161 |
| 27 | Co | cobalt | 167,400 | 178,100 | 189,300 | 204,500 | 214,100 | 920,870 | 966,023 |
| 28 | Ni | nickel | 169,400 | 182,700 | 194,000 | 205,600 | 221,400 | 231,490 | 992,718 | 1,039,668 |
| 29 | Cu | copper | 174,100 | 184,900 | 198,800 | 210,500 | 222,700 | 239,100 | 249,660 | 1,067,358 | 1,116,105 |
| 30 | Zn | zinc | 179,100 |
| 36 | Kr | krypton | 85,300 | 90,400 | 96,300 | 101,400 | 111,100 | 116,290 | 282,500 | 296,200 | 311,400 | 326,200 |
| 42 | Mo | molybdenum | 87,000 | 93,400 | 98,420 | 104,400 | 121,900 | 127,700 | 133,800 | 139,800 | 148,100 | 154,500 |