what is ionisation energy?

Question

how can i find ionisation energy?

Answer 1

In the context of atomic physics, ionization energy is the energy required to liberate a negatively charged electron from its orbital around a positively charged nucleus.  Quantum physics provides the tools for calculating ionization energy.  In essence, an electron in an atomic orbital has negative total energy and therefore is bound to the atom.  If it absorbs sufficient energy, then its energy can rise to zero or above, and then it becomes a free electron.  The ionization energy equals the absolute value of the total energy of the electron in its orbital.