CSSA Question on Ionising Energy (Quanta to Quarks) (1 Viewer)

[astron]

Does anyone actually know where Ionising Energy is supposed to be in the Quanta to Quarks course?

If so, how did you do the question?

 

[Chand]

im not sure, i didnt to that Q or finished the topic. A suggestion is that it would somehow be related to the ionising ability in alpha, beta and gamma, and thus how they are used in medicine/agriculture/industry...hope that helps..

 

[astron]

actually, it was a calculation question, asking for the ionising energy of a hydrogen atom

 

[Saul]

you use that guys equation... ummm... forget his name, but it has rhybergs constant, and you work out the energy if it goes to an infinite quantum number level thingy.

 

[deyveed]

What the hell is ionising energy?

 

[jims]

its the energy that's needed to completely remove an electron from an atom.

for this question, you use that equation...yeh i forget the name too...but you put in n(final) as infinity and n(initial) as 1.
now you know the wavelength of the photon needed (which turns out to be 1/-R).
then put that into E=hc/wavelength (it comes out nicely as -hcR) and that should get you -13.6eV

 

[deyveed]

ohh
You know this eV stuff, do you just get the energy from E=hf and times that with 931.5 or something to change it to eV?

 

[PoLaRbEaR]

Converting joules to eV:
number of joules divided by 1.6x10^-19

 

[Mathematician]

.....

For some reason the 1st ionising energy is the electrons total energy in the stationary state given by

E(n)= - ( 2pi k^2 e^4 m)/(h^2 n^2)

I got this from the excel - it works out to be 13.6eV

but i dont know why or if we are required to know this formula along with the other long ones in the xcel book.