A double ionised lithium atom is hydrogen like with atomic number `3` (i)Find the wavelength of the radiation to excite the electron in `Li^(++)`from the first to the third bohr orbit (lonisection energy of the hydrogen atom equals `13. 6)` (ii) How many spectral lines are observed in the emission spetrum of the above excled system ?

A double ionised lithium atom is hydrogen like with atomic number `3`

1.	A double ionised lithium atom is hydrogen like with atomic number `3` (i)Find the wavelength of the radiation to excite the electron in `Li^(++)`from the first to the third bohr orbit (lonisection energy of the hydrogen atom equals `13. 6)` (ii) How many spectral lines are observed in the emission spetrum of the above excled system ?
Answer» Correct Answer - A::B::C::D (i)` E_(0) = (13.6)/(n^(2))Z^(2) eV //atom ` for `Li^(2+ ), Z = 3 :. E_(n) = (-13.6 xx 9)/(n^(2)) eV atom` `:. E_(1) = (13.6 xx 9)/(1) and E_(3) = -(13.6 xx 9)/(9) = - 13.6` ` deltaE = E_(3)-E_(1) = - 13.6 - (-13.6 xx 9)` `= 13.6 xx 8 = 108.8eV// atom ` `lambda= (12400)/(E(in eV)) Å= (12400)/(108.8) = 114Å`

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