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Periodic trend

First Ionisation Energy

Energy needed to strip the outermost electron. Sawtooths upward across each period and peaks at the noble gases.

First Ionisation Energy plotted against atomic numberFirst Ionisation Energy for 104 of the 118 elements, from 376 to 2,372 kJ/mol. Energy needed to strip the outermost electron. Sawtooths upward across each period and peaks at the noble gases.12345673768751,3741,8732,372 Hydrogen (H): 1,312 kJ/mol Helium (He): 2,372 kJ/mol Lithium (Li): 520 kJ/mol Beryllium (Be): 900 kJ/mol Boron (B): 801 kJ/mol Carbon (C): 1,087 kJ/mol Nitrogen (N): 1,402 kJ/mol Oxygen (O): 1,314 kJ/mol Fluorine (F): 1,681 kJ/mol Neon (Ne): 2,081 kJ/mol Sodium (Na): 496 kJ/mol Magnesium (Mg): 738 kJ/mol Aluminium (Al): 578 kJ/mol Silicon (Si): 787 kJ/mol Phosphorus (P): 1,012 kJ/mol Sulfur (S): 1,000 kJ/mol Chlorine (Cl): 1,251 kJ/mol Argon (Ar): 1,521 kJ/mol Potassium (K): 419 kJ/mol Calcium (Ca): 590 kJ/mol Scandium (Sc): 633 kJ/mol Titanium (Ti): 659 kJ/mol Vanadium (V): 651 kJ/mol Chromium (Cr): 653 kJ/mol Manganese (Mn): 717 kJ/mol Iron (Fe): 763 kJ/mol Cobalt (Co): 760 kJ/mol Nickel (Ni): 737 kJ/mol Copper (Cu): 746 kJ/mol Zinc (Zn): 906 kJ/mol Gallium (Ga): 579 kJ/mol Germanium (Ge): 762 kJ/mol Arsenic (As): 947 kJ/mol Selenium (Se): 941 kJ/mol Bromine (Br): 1,140 kJ/mol Krypton (Kr): 1,351 kJ/mol Rubidium (Rb): 403 kJ/mol Strontium (Sr): 550 kJ/mol Yttrium (Y): 600 kJ/mol Zirconium (Zr): 640 kJ/mol Niobium (Nb): 652 kJ/mol Molybdenum (Mo): 684 kJ/mol Technetium (Tc): 702 kJ/mol Ruthenium (Ru): 710 kJ/mol Rhodium (Rh): 720 kJ/mol Palladium (Pd): 804 kJ/mol Silver (Ag): 731 kJ/mol Cadmium (Cd): 868 kJ/mol Indium (In): 558 kJ/mol Tin (Sn): 709 kJ/mol Antimony (Sb): 834 kJ/mol Tellurium (Te): 869 kJ/mol Iodine (I): 1,008 kJ/mol Xenon (Xe): 1,170 kJ/mol Cesium (Cs): 376 kJ/mol Barium (Ba): 503 kJ/mol Lanthanum (La): 538 kJ/mol Cerium (Ce): 534 kJ/mol Praseodymium (Pr): 527 kJ/mol Neodymium (Nd): 533 kJ/mol Promethium (Pm): 540 kJ/mol Samarium (Sm): 545 kJ/mol Europium (Eu): 547 kJ/mol Gadolinium (Gd): 593 kJ/mol Terbium (Tb): 566 kJ/mol Dysprosium (Dy): 573 kJ/mol Holmium (Ho): 581 kJ/mol Erbium (Er): 589 kJ/mol Thulium (Tm): 597 kJ/mol Ytterbium (Yb): 603 kJ/mol Lutetium (Lu): 524 kJ/mol Hafnium (Hf): 659 kJ/mol Tantalum (Ta): 761 kJ/mol Tungsten (W): 770 kJ/mol Rhenium (Re): 760 kJ/mol Osmium (Os): 840 kJ/mol Iridium (Ir): 880 kJ/mol Platinum (Pt): 870 kJ/mol Gold (Au): 890 kJ/mol Mercury (Hg): 1,007 kJ/mol Thallium (Tl): 589 kJ/mol Lead (Pb): 716 kJ/mol Bismuth (Bi): 703 kJ/mol Polonium (Po): 812 kJ/mol Astatine (At): 899 kJ/mol Radon (Rn): 1,037 kJ/mol Francium (Fr): 380 kJ/mol Radium (Ra): 509 kJ/mol Actinium (Ac): 499 kJ/mol Thorium (Th): 587 kJ/mol Protactinium (Pa): 568 kJ/mol Uranium (U): 598 kJ/mol Neptunium (Np): 605 kJ/mol Plutonium (Pu): 585 kJ/mol Americium (Am): 578 kJ/mol Curium (Cm): 581 kJ/mol Berkelium (Bk): 601 kJ/mol Californium (Cf): 608 kJ/mol Einsteinium (Es): 619 kJ/mol Fermium (Fm): 627 kJ/mol Mendelevium (Md): 635 kJ/mol Nobelium (No): 642 kJ/mol Lawrencium (Lr): 470 kJ/mol Rutherfordium (Rf): 580 kJ/mol Period
104 of 118 elements have a measured value.376 – 2,372 kJ/mol

Highest

  1. 1He Helium2,372
  2. 2Ne Neon2,081
  3. 3F Fluorine1,681
  4. 4Ar Argon1,521
  5. 5N Nitrogen1,402

Lowest

  1. 1Cs Cesium376
  2. 2Fr Francium380
  3. 3Rb Rubidium403
  4. 4K Potassium419
  5. 5Lr Lawrencium470

14 elements have no measured value for this property, so they are left out of the plot rather than drawn as zero. Almost all of them are synthetic elements that have never existed in weighable quantities.

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