Ionization Energy Main Page
First year chemistry curriculum concepts
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Z-matrix to Cartesian Converter
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Glossary of Terms
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SUCCEED's Computational Chemistry
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- Ion - An atom or group of atoms which has a net charge, ie, there are not
enough electrons to properly balance out the charge of the nuclei. This
happens when an electron is added or ejected from the atom.
- Ionization energy is the amount of energy needed to eject an electron from
- Some atoms have multiple ionization energies when they are able to add or
remove more than one electron.
- Ionization energies (IE) increase from bottom to top and from left
to right across the periodic table.
- Atomic size increase from top to bottom and from right to left across the
- Electron Affinity (EA) - the amount of energy needed to add an
electron to an atom.
- IE = EA
- EA = energy of the Lowest Unoccupied Molecular
- Subtraction Method: IE = Energy of the ion - Energy of the neutral
Back to Background Reading
- Frontier Orbitals - a collective term for the Highest
Occupied Molecular Orbital (HOMO) and the Lowest
Unoccupied Molecular Orbital (LUMO)
- Frontier Orbitals help calculate electronegativity, hardness, and
- Koopman's Theory: The IE is equal to the HOMO energy (this method
is exact for only hydrogenic atoms)