The maximum potential energy that an atom can have is 0J, at which point the electron has essentially been removed from the nucleus; thus the atom is ionized. In normal hydrogen atom, when the electron occupies its lowest available energy state the atom is said to be in its ground state. Explain how much energy will it take to ionize a hydrogen atom in its ground state? Determine the wavelength of light that would be needed to effect this ionization? Find out the series of spectral lines to which this wavelength belongs.