15 Facts About Ionization energy

In physics and chemistry, ionization energy, ionisation energy is the minimum energy required to remove the most loosely bound electron of an isolated gaseous atom, positive ion, or molecule.

Ionization energy is positive for neutral atoms, meaning that the ionization is an endothermic process.

Nth ionization energy refers to the amount of energy required to remove the most loosely bound electron from the species having a positive charge of .

Term ionization potential is an older and obsolete term for ionization energy, because the oldest method of measuring ionization energy was based on ionizing a sample and accelerating the electron removed using an electrostatic potential.

At a certain wavelength and frequency of light, the light quanta, whose Ionization energy is proportional to the frequency, will have Ionization energy high enough to dislodge the least bound electrons.

The ionization energy will be the energy of photons h?i that caused a steep rise in the current: Ei = h?i.

Ionization energy is a periodic trend within the periodic table.

Ionization energy values tend to decrease on going to heavier elements within a group as shielding is provided by more electrons and overall, the valence shells experience a weaker attraction from the nucleus, attributed to the larger covalent radius which increase on going down a group Nonetheless, this isn't always the case.

In general, the computation for the Nth ionization energy requires calculating the energies of and electron systems.

The second way of calculating ionization energies is mainly used at the lowest level of approximation, where the ionization energy is provided by Koopmans' theorem, which involves the highest occupied molecular orbital or "HOMO" and the lowest unoccupied molecular orbital or "LUMO", and states that the ionization energy of an atom or molecule is equal to the energy of the orbital from which the electron is ejected.

In Figure 1, the lower potential Ionization energy curve is for the neutral molecule and the upper surface is for the positive ion.

In many circumstances, the adiabatic ionization energy is often a more interesting physical quantity since it describes the difference in energy between the two potential energy surfaces.

However, due to experimental limitations, the adiabatic ionization energy is often difficult to determine, whereas the vertical detachment energy is easily identifiable and measurable.

Electron binding Ionization energy is a generic term for the minimum Ionization energy needed to remove an electron from a particular electron shell for an atom or ion, due to these negatively charged electrons being held in place by the electrostatic pull of the positively charged nucleus.

Work function is the minimum amount of Ionization energy required to remove an electron from a solid surface, where the work function for a given surface is defined by the difference.