[Jules18]

Here's the question:

Calculate the wavelength of the light that is absorbed for the electron's transition from n=5 to n=6 in Fe25+ ion. (ans in nm.)

1/λ = R_H[(1/n₁²) - (1/n₂²)]

R_H = 1.097*10⁷
n₁ = 5
n₂ = 6

here's what I got:
λ = 7.458*10³ nm

But the answer key says it's wrong.  Does anyone want to try it?

[Ak]

what answer does the key give?

if iron is a hydrogen like element (im not sure) and i use the rydberg i get 7591 nm which is a bit off of urs

[Jules18]

I don't have a real answer key, actually.. I'm doing these questions online and when I enter an answer, it's programmed to tell me whether I'm right or not. 

I tried yours, and it's still telling me "incorrect", so I'm not sure what the problem is. 

[Jules18]

Fe+25 (although I have no idea why that would ever exist in nature - these questions are ridiculous, why don't they just say H?) would have one electron, so I think it would qualify as hydrogen-like. 
If it wasn't, would there be any way to solve it?

[Borek]

You use incorrect value for Rydberg constant. R_H - what does H stands for?

Fe+25 (although I have no idea why that would ever exist in nature - these questions are ridiculous, why don't they just say H?)

Not very likely to be observed, but technically possible. Besides, the questions is not ridiculous, it just proved you don't understand how the model works and what parameters are important when calculating wavelengths.

[savy2020]

Well the answer seems to be correct though you may need to check the number of significant figures.
What I mean is -If it has been programmed that 7.46*10³ is correct answer it may not accept 7.458*10³ as correct.
So don't bother about it

[Borek]

Well the answer seems to be correct

Sure. What does H in R_H stands for?

[savy2020]

OH!!!  
Right H stands for hydrogen
There should be another factor Z² to RHS of the equation 1/λ = RH[(1/n12) - (1/n22)]

Right Borek?

[Jules18]

I have no idea what you guys are talking about.  ... Am I using the wrong R_H?  and what about Z² ?

[savy2020]

Hey
THe equation should've been
1/λ = R_H*Z²[(1/n12) - (1/n22)]
here Z=26 (Fe)

[Jules18]

Thanks so much I didn't know about that at all. 

[Borek]

http://en.wikipedia.org/wiki/Rydberg_constant

When you solve for energy of the electron in the Bohr model, you find that energy depends on the charge of nucleus - the higher the charge, the higher the energy. Charge of nucleus is denoted by Z. For hydrogen it is 1, so it is ignored, but for other hydrogen-like ions (that is, ions with exactly one electron) Z is an important factor.

[savy2020]

When you solve for energy of the electron in the Bohr model, you find that energy depends on the charge of nucleus - the higher the charge, the higher the energy. Charge of nucleus is denoted by Z. For hydrogen it is 1, so it is ignored, but for other hydrogen-like ions (that is, ions with exactly one electron) Z is an important factor.
@Borek

Thanks for reminding me that I nearly forgot