Question

How do you calculate the ionization energy of an element?

Answer 1

Use the Rydberg Equation `DeltaE_i` = `A(1/n_f^2 - 1/n_i^2)` where `A = 2.18xx10^-18"Joules"`; `n_f = oo`; `n_i = "starting energy level".`

Explanation:

For the Hydrogen Atom, ionization from the ground state where `n_i = 1` => `DeltaE_(izn)=2.18xx10^-18J(1/(oo)^2 - 1/(1)^2)` = `-2.18xx10^-18"Joules"` to remove the electron from n = 1 energy level to `n=oo`. The negative indicates that on 'gain' of electron, `2.18xx10^-18`Joules energy is released, but on removal, `DeltaE` should be greater than zero indicating the gain of energy to remove the electron. `Delta E_(removal)`=`DeltaE_("gained")`.

The `2.18xx10^-18` Joules is per atom#

=> `"Joules"/"mole"` = `(2.18xx10^-18 j/"atom")` `(6.02xx10^23"atoms"/"mole")` = `1,351,600 "joules"/"mole" =`1352`"Kj"/"mole"`. This corresponds favorably with the published 1st ionization energy of the Hydrogen atom.