# Ionization Energy of Helium Atom | 24.6 eV

• physicsmaths1613
In summary, the energy required to remove both electrons from a helium atom is related to the first ionization energy by the equation IP2 = IP1*Z2. This equation can be applied because He+ is a hydrogen-like species and Bohr's model is applicable to it. However, Bohr's model is not applicable to the initial He atom with two electrons. The source of this equation is unknown, but it can be interpreted as the energy required to remove the second electron from He+. This interpretation results in the correct value for IP2, which is twice the value of IP1.

## Homework Statement

The energy required to ionize a helium atom is 24.6 eV. The energy required to remove both the electrons from He atom would be?

## The Attempt at a Solution

My textbook says-
IP1= 24.6 eV
IP 2= IP1*Z2
How can they relate the first ionization energy to the second one? The Bohr's atom can be used only for Hydrogen like species and He atom is not Hydrogen like, only it's ion is. How did they relate it?

He+ is a hydrogen like species as it has one electron.So Bohr's model is applicable on it.

harsh_sinha said:
He+ is a hydrogen like species as it has one electron.So Bohr's model is applicable on it.
But what about intial He atom with 2 electrons?

physicsmaths1613 said:
But what about intial He atom with 2 electrons?
Bohr's model is not applicable for He atom.Besides if we use this equation to calculate IP2 then the result would be twice of the actual value.
It would be great if you share the source of this equation.

• physicsmaths1613
physicsmaths1613 said:
IP 2= IP1*Z2
I can only get the right answer from that by interpreting the IP2 as the energy to remove the second electron from He+, and the IP1 as the energy required to ionise H (which makes sense).

• physicsmaths1613