Question

-Calculate the third ionization of Lithium ( this requires no approximations or assumptions)?

-Calculate the firse and second ionization energies of lithium using slaters rule?

-Calculate the first and second ionization enegies of lithium using the rules of Clementi and Raimondi?

Answer 1

The energy of an electron in the n th Bohr orbit of a H-like atom ( one electron systems) like H,He⁺ ,Li⁺⁺ .Be⁺⁺⁺ etc is given by

E_n = - Z² x 13.6 eV / n²

Z = Atomic number ;     n = quantum number

For Li , Z = 3

Therefore for Li++

E₁ = - 3² x 13.6 eV / 1² = - 122.4 eV

E₁ = - 122.4 eV means that when an electron at infinite distance falls into the first Bohr orbit, 122.4 eV energy is released (hence the negative sign).

Therefore the energy required to remove an electron in the first Bohr orbit to infinite distance is +122.4 eV

Therefore,

the ionization energy of Li++ = + 122.4 eV

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Ionization energy in Joules

1eV = 1.602 x 10 ^-19 J

Therfore, 122.4 eV = 122.4 x 1.602 x 10 ^-19 J = 3.48 x 10 ^-17 J

The ionization energy of Be⁺⁺⁺ = 1.96 x 10 ^-17 J

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