Ionization Potential Calculator
Look up and calculate ionization energies (ionization potentials) for elements with unit conversions.
Ionization Parameters
Periodic Trends
- • IE increases across a period (left → right)
- • IE decreases down a group (top → bottom)
- • Successive IEs always increase
- • Large jump when removing core electrons
Ionization Energy
495.8 kJ/mol
Na → Na⁺ + e⁻
In Electron Volts
5.139 eV
In Hartree
0.1888
Per Atom (Joules)
8.2331e-19 J
Metallic Character
Highly metallic (easily loses electrons)
Trend Analysis
First ionization energy - easiest electron to remove
About Ionization Energy
Ionization energy (or ionization potential) is the minimum energy required to remove an electron from a gaseous atom or ion. The first ionization energy removes the outermost electron, while successive ionization energies remove additional electrons. Ionization energies generally increase across a period due to increasing nuclear charge and decrease down a group due to increased shielding and larger atomic radius.
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