What is the maximum radiation wavelength required to ionize the remaining electron near the nucleus

What is the maximum radiation wavelength required to ionize the remaining electron near the nucleus, which is in the ground state with an energy of -4.3 eV?

There is a known formula expressing the energy of a photon in terms of frequency:

E = hv.

The frequency, in turn, can be expressed in terms of the photon wavelength:

v = c / λ;

E = ch / λ;

λ = ch / E.

To snatch an electron from an ionized atom, a photon must transfer to it energy E, which in absolute value must be equal to the binding energy of the electron with the nucleus Ec = -4.3 eV. We substitute E = 4.3 eV into the formula.

λ = (3 * 10 ^ 8 m / s * 4.135 * 10 ^ -15 eV * s) / (4.3 eV) = 2.88 * 10 ^ -7 m = 288 nm.

Answer: 288 nm.