What is the n value for Li2+ ion in the Bohr model of the atom?

[physicsnobrain]

Homework Statement

In the equation for the bohr model of the atom, what is the n value for Li2+ ion?

Homework Equations

E = -2.178 x 10^-18J(z^2/n^2)

The Attempt at a Solution

Since it is Li2+ that means it has 1 electron. So z = 1. Now I have an equation with 2 variables (impossible to solve).

I don't know what E is and I have to find n. Does anyone have any idea on how to do this?

 

[nasu]

z is the charge of the nucleus and is not 1 for Li.
For the rest, it may help to post the complete text of the problem.

 

[physicsnobrain]

z is the charge of the nucleus and is not 1 for Li.
For the rest, it may help to post the complete text of the problem.

It's Li2+ not Li. And this is the complete text of the problem...

 

[nasu]

It does not matter. The charge of the nucleus is 3e for Li, Li+, Li2+.
So z=3.

But n can take any value so the question does not seem to make sense.

 

[physicsnobrain]

IF the question is instead: In the equation for the bohr model of the atom, what is the z value for Li2+ ion?


Does this make more sense?

 

[DrClaude]

IF the question is instead: In the equation for the bohr model of the atom, what is the z value for Li2+ ion?


Does this make more sense?

Yes.

 

[physicsnobrain]

Yes.

Well isn't there still three unknown variables Energy and n value and z value?

 

[Borek]

But you are not asked to find all three, just to tell what (most likely) Z is.

As worded question doesn't make sense, unless it asks for Z, not n.

 

[Enigman]

Well isn't there still three unknown variables Energy and n value and z value?

What is Z? What does it mean? What is Z for lithium?
(yay! 200th post)

 

[physicsnobrain]

The question exactly as it appears word for word is: In the equation for the Bohr model of the atom, what is the Z value for Li2+ ion?

I am still unsure of how to go about this question. Which equation should I use?

 

[DrClaude]

The question exactly as it appears word for word is: In the equation for the Bohr model of the atom, what is the Z value for Li2+ ion?

I am still unsure of how to go about this question. Which equation should I use?

You had the right equation in the OP. Go back in your notes/textbook and find what the $Z$ stands for.

 

[physicsnobrain]

You had the right equation in the OP. Go back in your notes/textbook and find what the $Z$ stands for.

it stands for nuclear charge.

 

[Borek]

And what is nuclear charge for lithium?

 

[physicsnobrain]

And what is nuclear charge for lithium?

It is +3. So there is no need to use the equation for this problem? Seems more challenging than that.

 

[Borek]

No, it is as simple as that. You were making it more difficult than it is from the very beginning.