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# help with as physics :( watch

1. in its ground state the atom absorbs 2.3exp-19J of energy

i) calculate all the possible frequencies of radiation that the atom may subsequently emit.

ii)how much energy in eV would be required to ionise the atom in its ground state?

the energy levels of an atom: (this was the diagram included)
energy/exp-19J
level D 0.0 (ionised state)
level C -2.3
level B -2.5
level A -4.6 (ground state)

NOTE- when i have written exp it means x10. i didn't know how to write it in standard form without the power looking making it one big number.
any help would be great, thanks in advance.
2. This is AS physics? Seems a bit complex...

Your course must be waay different.

Anway, I would guess that Planck's equation is needed for part (i), E=hf.

2.3exp-19 divided by h (Plancks constant) would give you the frequency. Not sure about 'different possible' frequencies.

And surely the answer to part (ii) is just 4.6exp-19? Cos that's how much energy it has before it is ionised and according to your numbers it has no energy when ionised, although that sounds slightly wrong.
3. How far have you got with this?

Remember the formula E = hf.

(Original post by alex910_2)
according to your numbers it has no energy when ionised, although that sounds slightly wrong.
The potential energy of an electron is defined to be 0 when it has been ejected from the atom. All the bound states have negative potential energy - this is analogous to the energy of an orbiting body.
How far have you got with this?

Remember the formula E = hf.

The potential energy of an electron is defined to be 0 when it has been ejected from the atom. All the bound states have negative potential energy - this is analogous to the energy of an orbiting body.
to be frank i havn't got no where with this question. my teacher printed out 5 a3 sheets of past exam questions and i've done all but three and this is one i'm really stuck on.
i don't understand what it means by 'absorbs 2.3exp-19J of energy', because when i've had to work out frequency on any other question its just been work out the frequency of an emitted photon and i've used:
f=E1-E2/h
5. It simply means that the electron gains 2.3 * 10^-19 J of energy - probably by being hit by a photon or something. That extra energy allows it to be 'knocked' into one of the higher states - but not any state requiring a larger energy than the electron has...
It simply means that the electron gains 2.3 * 10^-19 J of energy - probably by being hit by a photon or something. That extra energy allows it to be 'knocked' into one of the higher states - but not any state requiring a larger energy than the electron has...
okay so an electron receives that energy, and it currently has -4.6*10^-19J.
so would i add those together to find the energy of the atom
then divide that answer by h to get f. (like using f=E/h)
or am i talking nonsense?

edit: the question says all the possible frequencies, so that must be wrong as i only get one answer
7. You're exactly right so far - just remember that as well as jumping from -2.3 to -4.6, it can jump from -2.3 to -2.5, and then from -2.5 to -4.6.
You're exactly right so far - just remember that as well as jumping from -2.3 to -4.6, it can jump from -2.3 to -2.5, and then from -2.5 to -4.6.
yay that's gave me a ray of hope

but the atom never jumped from -2.3 to -4.6 did it?
didn't it just gain energy from a collision so hasn't it moved from -4.6 to -2.3?
and then the other calculations would be the same but moving up to higher states?

and also the question says from ground state to atom absorbs the energy, so i can't calculate it from higher states surely?
9. (Original post by bubba.ok)
but the atom never jumped from -2.3 to -4.6 did it?
didn't it just gain energy from a collision so hasn't it moved from -4.6 to -2.3?
and then the other calculations would be the same but moving up to higher states?
It goes up the levels, and then drops back down - you put in energy (and it absorbs it) to jump up to higher levels, and then it jumps down again - and gives out energy in the form of a photon.

It's the energy released when it jumps back down that you're calculating.
It goes up the levels, and then drops back down - you put in energy (and it absorbs it) to jump up to higher levels, and then it jumps down again - and gives out energy in the form of a photon.

It's the energy released when it jumps back down that you're calculating.
thanks so much for all your help, i'd rep you but it's about as much use as a slap round the face with a wet fish.

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