Have I answered this AS ionisation energy question well? Watch

Mixedraceguy
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Hey I'm not sure if I've answered this question well and how many marks would I have got out of three, here it is

An element X has the following values in KJ Mol-1 for successive ionisation energies 1093,2559,4627,6229,37838,47285

Identify which group in the periodic table it is in and explain why

Element X is in group 4 as there is a massive jump between the 4th and 5th ionisation energies which shows there are four electrons in the outer shell
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Kian Stevens
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Yes. You're just missing one piece of information, and that's what the large jump actually means.
The large jump means that electrons are being removed from a new shell closer to the nucleus, meaning there's a greater attractive force on them (less shielding), and so more energy is needed to overcome this force to remove them.
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Mixedraceguy
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(Original post by Kian Stevens)
Yes. You're just missing one piece of information, and that's what the large jump actually means.
The large jump means that electrons are being removed from a new shell closer to the nucleus, meaning there's a greater attractive force on them (less shielding), and so more energy is needed to overcome this force to remove them.
Oh yes of course as there are less electrons to shield the nuclear charge right?
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Kian Stevens
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(Original post by Mixedraceguy)
Oh yes of course as there are less electrons to shield the nuclear charge right?
Pretty much, yes. And because the electrons are closer to the nucleus don't forget. Great answer if you were to say these things!
Also, I don't mean to nitpick but I'd be a little more modest on my descriptions, i.e. 'large' instead of 'massive'.
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Mixedraceguy
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(Original post by Kian Stevens)
Pretty much, yes. And because the electrons are closer to the nucleus don't forget. Great answer if you were to say these things!
Also, I don't mean to nitpick but I'd be a little more modest on my descriptions, i.e. 'large' instead of 'massive'.
Right I suppose a change of 31609 KJ mol-1 isn't that big compared to some elements?
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GP-Luffy
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You could rephrase your answer to, the big gap between the 4th and 5th ionisation energy is due to the 5th electron is being in the next energy gap. More energy will be required to remove electrons from a higher energy level due to the decrease in shielding effect. The decrease in shielding effect is due to the decrease in number of shells.

Of course it may or may not be necessary to write that much, just refer to the number of marks allocated. This answer should get you the maximum marks, but is it's only a 1 mark question, your method is answering is sufficient.
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Kian Stevens
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(Original post by Mixedraceguy)
Right I suppose a change of 31609 KJ mol-1 isn't that big compared to some elements?
It's not necessarily about that, it's just that I personally would be a bit more modest with the adjectives I use. For example, using 'big' would be a bit vague, but 'massive' could be seen as a bit over-the-top; 'large' is just in between.

(Original post by GP-Luffy)
You could rephrase your answer to, the big gap between the 4th and 5th ionisation energy is due to the 5th electron is being in the next energy gap. More energy will be required to remove electrons from a higher energy level due to the decrease in shielding effect. The decrease in shielding effect is due to the decrease in number of shells.

Of course it may or may not be necessary to write that much, just refer to the number of marks allocated. This answer should get you the maximum marks, but is it's only a 1 mark question, your method is answering is sufficient.
This is a three mark answer, I'd probably give you two marks depending on what the mark scheme wanted, simply because you didn't say what group X is in.
However, 'next energy gap' is a bit ambiguous, and electrons will actually be removed from lower energy levels; non-intuitive I know, but higher energy levels are further away from the nucleus, so their attractive force decreases and their shielding increases.
Last edited by Kian Stevens; 7 months ago
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Alropsr
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(Original post by Mixedraceguy)
Hey I'm not sure if I've answered this question well and how many marks would I have got out of three, here it is

An element X has the following values in KJ Mol-1 for successive ionisation energies 1093,2559,4627,6229,37838,47285

Identify which group in the periodic table it is in and explain why

Element X is in group 4 as there is a massive jump between the 4th and 5th ionisation energies which shows there are four electrons in the outer shell
You also have to say the big jump shows a new shell
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GP-Luffy
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(Original post by Kian Stevens)
This is a three mark answer, I'd probably give you two marks depending on what the mark scheme wanted, simply because you didn't say what group X is in.
However, 'next energy gap' is a bit ambiguous, and electrons will actually be removed from lower energy levels; non-intuitive I know, but higher energy levels are further away from the nucleus, so their attractive force decreases and their shielding increases.
Not necessarily a three mark question since I have encountered it as a 2 mark. Also, unless specifically stated the first value is the 1st ionisation energy, you cannot assume which group is X in. I agree on the energy level part though, my answer is a bit wrong but I based this on the CIE scheme and I usually get full marks for this sort of question, not sure how other exam boards will view it like.
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Kian Stevens
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(Original post by GP-Luffy)
Not necessarily a three mark question since I have encountered it as a 2 mark. Also, unless specifically stated the first value is the 1st ionisation energy, you cannot assume which group is X in. I agree on the energy level part though, my answer is a bit wrong but I based this on the CIE scheme and I usually get full marks for this sort of question, not sure how other exam boards will view it like.
The OP implied that this is a 3 mark question by saying they don't know how many marks they'd get out of 3, hence why I rated your comment 2/3 marks. The three marks are most likely for:
  • Stating which group element X is in,
  • Giving evidence in terms of ionisation energy,
  • Explaining the evidence.

So, the point of this question is to determine which group element X is in and why.
I'm not assuming it's in group 4, as it is in group 4, due to the large jump in ionisation energies between the 4th and 5th ionisations; if the question states that the energy values are for an element's successive ionisation energies, you can assume that the values start at the 1st ionisation energy. The question would state otherwise if this wasn't the case.
Last edited by Kian Stevens; 7 months ago
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