### E=R(1/n-1/n)?

Posted:

**Sun Apr 29, 2018 11:31 pm**I'm confused on how exactly Borh's equation is turned into E=R(1/n-1/n) when finding the difference in energy level?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=17&t=31224

Page **1** of **1**

Posted: **Sun Apr 29, 2018 11:31 pm**

I'm confused on how exactly Borh's equation is turned into E=R(1/n-1/n) when finding the difference in energy level?

Posted: **Mon Apr 30, 2018 1:24 am**

ΔE=Ef-Ei

En= -hR/n^2

ΔE= -hR/nf^2 - (-hR/ni^2)

ΔE= hR/ni^2 - hR/nf^2

V=R(1/ni^2 - 1/nf^2)

ΔE/h= R(1/ni^2 - 1/nf^2)

ΔE=hR(1/ni^2 - 1/nf^2)

ΔE=hR/ni^2 - hR/nf^2

En= -hR/n^2

ΔE= -hR/nf^2 - (-hR/ni^2)

ΔE= hR/ni^2 - hR/nf^2

V=R(1/ni^2 - 1/nf^2)

ΔE/h= R(1/ni^2 - 1/nf^2)

ΔE=hR(1/ni^2 - 1/nf^2)

ΔE=hR/ni^2 - hR/nf^2

Posted: **Wed May 09, 2018 12:54 am**

Are we supposed to use E= R(1/n-1/n) or E= hR/n^2 when finding the difference in energy levels?

Posted: **Wed May 09, 2018 12:38 pm**

When given two energy levels (n1,n2) or a beginning and ending energy state you can use the E=R(1/n-1/n). The other formula, E=-R(h/n^2) is used to find the energy of an electron in the nth state of a hydrogen atom specifically

Posted: **Wed May 09, 2018 8:49 pm**

I am not 100% sure, but I think the equation R(1/n^2-1/n^2) is used to find the frequency, where the first one is initial and the second one is final because when deriving it you would get a negative final plus a positive initial, therefore it can switch places to make it a little simpler. (This was in my notes from discussion)

Posted: **Thu May 10, 2018 9:06 pm**

E=R(1/n2^2-1/n1^2) is the equation to specifically find the change in energy. The E= -hR/n^2 is for one specific energy level

Posted: **Thu May 10, 2018 10:22 pm**

The book says Frequency = R(1/n2^2-1/n1^2)

Posted: **Fri May 11, 2018 10:47 am**

If a problem states energy was emitted would the final answer be negative and if the problem asks energy was absorbed would the final answer be positive?