How to calculate the first ionization energy?

Question

Given [Ar] 4s2 4p, calculate the first ionization energy.

Answer 1

There are two main methods of calculating first ionization energy:

1)Subtraction Method
The first of two main methods which scientists use to calculate the ionization energy is the Subtraction Method. This method entails some experimentation. You first must find the energy value of the ion for which you are looking. Then, subtract the energy value of the neutral atom. This difference is the ionization energy for that ion. Your answers can be compared easily with literature values published in most chemistry books

2)Koopman's theory: The second main methods which scientists use to calculate the ionization energy is using Koopmans' Theory, a more advanced method. Two key characteristics of an atom or molecule that are very important to scientists are the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Together, these two orbitals are called the frontier orbitals. The HOMO can be found by locating the outer most orbital containing an electron

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Answer 2

wouldn t it be energy for ionization(E) = -2.178*10^(-18) J / (n^2) E = -2.178*10^(-18) J / (5^2) = -2.178*10^(-18) J / (25) = -8.712*10^(-20) J it needs to be positive though because that is how much energy needs to be put into the atom so: E = 8.712*10^(-20) J

Answer 3

1st u have to calculate the Z effective charge. 4 that u have a particular rule through which u can determine it.just go through any book where screening effect and Zeffect r consider.