Question

Page
& Ionisation energy of an element 288 kJ/mol
Wavelength of Photon require to just ionize.
Calculate
3​

Answer 1

:

The first thing to do here is to calculate the ionization energy for one atom of aluminium,

Al

, by suing the fact that you know the energy needed to ionize one mole of atoms of aluminium.

As you know, one mole of any element contains exactly

6.022

⋅

10

23

atoms of that element, as given by Avogadro's number.

You can thus say that the energy needed to ionize one atomof aluminium is equal to

577.6

kJ

mol

⋅

1

mole Al

6.022

⋅

10

23

atoms of Al

=

9.5915

⋅

10

−

22

kJ / atom

Now, the energy of a photon is directly proportional to its frequency as given by the Planck - Einstein equation

∣

∣

∣

∣

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

a

a

E

=

h

⋅

ν

a

a

∣

∣

−−−−−−−−−−−−−

Here

E

- the energy of the photon

ν

- its frequency..