Possible frequencies of an electron

[aurao2003]

Hi
Could someone kindly clarify the following?

Homework Statement

In its ground state the atom absorbs 2.3 × 10–19J of energy from a collision with an electron.
(i) Calculate all the possible frequencies of radiation that the atom may subsequently emit.

Homework Equations

E=hf

The Attempt at a Solution

Using h as the Planck constant and E being given , I obtained a frequency of 3.5 x 10^14 Hz.

But how do I determine the possible frequencies?
Highly appreciate any suggestions.

 

[Stonebridge]

It depends what atom it is, and what the electron energy levels are.
As you haven't given this information it's impossible to say exactly.
The excited electron can then fall to lower energy states and emit a photon E=hf where E is the energy difference between two energy levels and f the frequency.

 

[aurao2003]

level D 0.0 (ionised state)
level C –2.3
level B –2.5
level A –4.6 (ground state)

Thats the energy levels.

The atom is not specified. The question just states an atom.

 

[Stonebridge]

Are the energy levels given in electron volts or are they all x 10^-19 J as in the question?
When you have determined that, work out which is the highest level the electron can move up to given the energy available from the collision.
Then, work out what energy will be lost by that electron when it falls back down to any of the states below it, releasing its energy as a photon.

 

[aurao2003]

I have worked it out and obtained a frequency. But its referring to range of frequencies. Thats where the confusion lies. The energy levels are as you stated.

 

[Stonebridge]

If it is initially in the ground state, which is the highest energy level the atom can jump up to as a result of gaining the energy from the collision?

 

[aurao2003]

That should be level D. But that would imply ionisation.

 

[Stonebridge]

I assumed in your peply in post 5 that you meant the energies are in units of 10^-19 J
If that were the case, giving 2.3 units of energy is not going to ionise the atom because that needs 4.6 units according to your info in post 3.

 

[aurao2003]

Thanks. Since I already know the frequency what is the correlation of the ground state?

 

[Stonebridge]

I think you have a basic misunderstanding of what's going on here.
The atom is excited from the ground state by the collision, which provides 2.3 x 10^-19 J of energy.
Which level can it (the atom) rise to above the ground state if given this energy? The answer is not D, that we have decided.

 

[aurao2003]

I think you have a basic misunderstanding of what's going on here.
The atom is excited from the ground state by the collision, which provides 2.3 x 10^-19 J of energy.
Which level can it (the atom) rise to above the ground state if given this energy? The answer is not D, that we have decided.

I think you might need to read my original post. The conversation is stretching but deviating from my initial question.

 

[aurao2003]

However, in response to your question it can rise to level c.

 

[Stonebridge]

So if the atom can rise to level C (we had to get to this point to answer the question) it can fall back directly to level B or level A.
It can also fall from B to A if it falls to B first.
So there are 3 possible transitions. Each transition involves a loss of energy for the atom, each can appear as a photon of energy E=hf.
(Which is what I said in my 1st answer in post 2. I couldn't be more specific as you hadn't given the full question, including the atomic energy levels. It usually pays on these forums to give the complete question. It certainly saves a lot of time.)

So now can you calculate the 3 frequencies that are possible for the atom to emit, having been raised to level C, and subsequently returning to the ground state either directly of via level B?

 

[aurao2003]

So if the atom can rise to level C (we had to get to this point to answer the question) it can fall back directly to level B or level A.
It can also fall from B to A if it falls to B first.
So there are 3 possible transitions. Each transition involves a loss of energy for the atom, each can appear as a photon of energy E=hf.
(Which is what I said in my 1st answer in post 2. I couldn't be more specific as you hadn't given the full question, including the atomic energy levels. It usually pays on these forums to give the complete question. It certainly saves a lot of time.)

So now can you calculate the 3 frequencies that are possible for the atom to emit, having been raised to level C, and subsequently returning to the ground state either directly of via level B?

Thanks. I will attempt your suggested line of reasoning. Sorry for the slow replies, but I am a full time worker! Ciao!