Question

What is Ionization Energy ?

Answer 1

An atom consists of a nucleus and electrons revolve around this nucleus in a circular orbit. The nucleus contains neutrons and positively charged particles, protons and hence the electrons are attracted to the nucleus. Energy has to be provided to overcome this force of attraction to remove the electron from atom or molecule.
After the electron has been eliminated from the atom, the atom acquires a unit positive charge and becomes a positively charged ion (cation). The energy required to remove an electron from a neutral gaseous atom so as to convert it into a positively charged ion is called Ionization Potential or first ionization potential or energy.