A doubly ionized lithium atom is hydrogen like with atomic number 3. Find the wavelength of the radiation required to excite the electron in `Li^(++)` from to the third Bohr orbit (ionization energy of the hydrogen atom equals 13.6 eV).

Answer

`113.74A^(@)`

Explanation

`Z=3,n_(1)=1, " "n_(2)=3`
`E_(n)=13.6xx(Z^(2))[(1)/(n_(1)^(2))-(1)/(n_(2)^(2))]=13.6xx9[(1)/(1)-(1)/(9)]`
`13.6xx9xx(8)/(9)=108.8eV`