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ionization energy

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yanks3455:
Ionization energy is defined as the minimum energy required to remove an electron from the ground state (n0) to infinity (n?). Determine the wavelength of radiation required to ionize the hydrogen electron from the n = 2 energy level. Calculate the energy (Joules) associated with this photon. (1 cm-1 = 1.986 x 10-23 J).

I've tried everyway of going about this and istill can't seem to get this problem right, anyways i tried using the formula:

1/wavelength = Rh/hc (1/nf^2 - 1/ni^2)

h= plancks constant 6.63e-34
c= speed of light 3e8
Rh= 2.179e-18
nf= final principal quantum number
ni= initial principal quantum number

maybe im using the wrong formula, who knows but i've been going at this for hours and i can't do it, any help would be appreciated

FeLiXe:
Actually all you have to do is calculate the energy of the n=2 electron. That goes by the formula E=-1/8*me^4/(h^2*eps0^2)*1/n^2

insert the values (reduced electron mass) and you get: E=-5.446*10^-19
that's the least amount of energy you need to ionize (i.e. make the electron's energy 0 or more) it. Use your other formula to get the minimum wavelength from that.

yanks3455:
wow i feel really stupid but thanks so much for the *delete me*!! can't believe it took me so long :)

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