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Successive Ionisation Energies

I understand what happens to each of the electrons in the first, second, third ionisation energies etc. However I don't understand the whole 'how much energy is required to remove an electron from each orbital'.

Hope this makes sense
Any help would be great!
Thanks, ravioiyears

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I cant PM you anymore because system says you've got too many PMs stored.

So you are talking about the trend in ionisation energy across a period, right?
Original post by ravioliyears
I understand what happens to each of the electrons in the first, second, third ionisation energies etc. However I don't understand the whole 'how much energy is required to remove an electron from each orbital'.

Hope this makes sense
Any help would be great!
Thanks, ravioiyears


Empty your PMs
Original post by TeachChemistry
Empty your PMs


Just emptied it
Original post by ravioliyears
I understand what happens to each of the electrons in the first, second, third ionisation energies etc. However I don't understand the whole 'how much energy is required to remove an electron from each orbital'.

Hope this makes sense
Any help would be great!
Thanks, ravioiyears


Read this and if you still are unsure after that ask again

http://www.chemguide.co.uk/atoms/properties/ies.html
Original post by ravioliyears
I understand what happens to each of the electrons in the first, second, third ionisation energies etc. However I don't understand the whole 'how much energy is required to remove an electron from each orbital'.

Hope this makes sense
Any help would be great!
Thanks, ravioiyears


Can you give an example of what you mean ?
Do you mean you are unsure as to what factors affect the IE from a orbital ,like stability,principal quantum number,nuclear charge etc. ?
Original post by Kadak
Can you give an example of what you mean ?
Do you mean you are unsure as to what factors affect the IE from a orbital ,like stability,principal quantum number,nuclear charge etc. ?


Sorry, I didn't clarify, I meant the trends that are visible in the graphs as the atomic mass increases, e.g. why it increases and then drops.
Ionisation energy increases. This is because the atom is becoming progressively positive (as you remove electrons); meaning there is a greater nuclear charge on the outer electron to be removed. The atomic radii also decreases. Thus the attraction the nucleus has on the outer electron is increased and so more energy is required for the removal of the electron, causing ionisation energy to increase.
Original post by ravioliyears
Sorry, I didn't clarify, I meant the trends that are visible in the graphs as the atomic mass increases, e.g. why it increases and then drops.

That graph represents all of the elements (according to their atomic number on the x axis). Elements in groups that are descending will have a fall in their ionisation energy because of the increasing shielding and atomic radii.
Original post by High Stakes
That graph represents all of the elements (according to their atomic number on the x axis). Elements in groups that are descending will have a fall in their ionisation energy because of the increasing shielding and atomic radii.


Thank you! And the shielding is caused by the orbitals.....?
Original post by ravioliyears
Sorry, I didn't clarify, I meant the trends that are visible in the graphs as the atomic mass increases, e.g. why it increases and then drops.


From the first two
Draw the shells
You can see you are removing electrons from the same principal quantum shell ,so there isnt any significent increase in electron shielding,but there is an increase in nuclear charge.
At 3,you have a new principal quantum shell so there are more core inner electron shells which increases electron shielding and makes it easier to remove the electron.
From 3 to 10,electrons are being removed from the same principal quantum shell,so again,no significent increase in electron shielding but increase in number of protons means greater electrostatic force of attraction to overcome ,so increase in IE energy.
From here onwards,the pattern just repeats itself.
Original post by ravioliyears
Thank you! And the shielding is caused by the orbitals.....?


By the increased number of shells.

If you go from left to right, the number of electrons increases but no new shells are added so shielding doesn't really change.

If you go from up to down, the number of electrons increases and the number of shells increase, so there is a greater shielding effect.
Original post by ravioliyears
Thank you! And the shielding is caused by the orbitals.....?


I would say core inner electron shells.Depend on the exam board I guess.
Original post by High Stakes
By the increased number of shells.

If you go from left to right, the number of electrons increases but no new shells are added so shielding doesn't really change.

If you go from up to down, the number of electrons increases and the number of shells increase, so there is a greater shielding effect.


Not sure if this is a exam board thing but we were taught to mention that the number of protons increases but the electron shielding outweighs it.
Thank you guys so much! Its all beginning to make sense now :smile:
Original post by Kadak
Not sure if this is a exam board thing but we were taught to mention that the number of protons increases but the electron shielding outweighs it.


Yeah, you need to mention it for the extra mark! It's outweighed or becomes negligible. :smile: OP will get the hang of it with enough exam practise to see what examiners want from them.

It's a fairly nice question to rack up marks.
Original post by High Stakes
By the increased number of shells.

If you go from left to right, the number of electrons increases but no new shells are added so shielding doesn't really change.

If you go from up to down, the number of electrons increases and the number of shells increase, so there is a greater shielding effect.

Hope you dont mind if I reformulate your answer .
Number of core inner electron shells increases.
When you go across a period,the electrons are being removed from the same principal quantum shell,so electron shielding is similar.

The number of protons increase,which increases the electrostati force of attraction between the nucleus and valence shell electrons,so the energy required to overcome this increases.
As you go down a group,the number of protons increase but this is outweighed by the increase in the number of inner core electron shells,so electron shielding increases.

The atomic radius increases.The electrostatic force of attraction between the nucleus and valence shell decreases ,so the enrgy required to overcome the weaker electrostatic forces of attraction between the nucleus and valence shell decreases.

:h::smile:.
Original post by Kadak
Hope you dont mind if I reformulate your answer .
Number of core inner electron shells increases.
When you go across a period,the electrons are being removed from the same principal quantum shell,so electron shielding is similar.

The number of protons increase,which increases the electrostati force of attraction between the nucleus and valence shell electrons,so the energy required to overcome this increases.
As you go down a group,the number of protons increase but this is outweighed by the increase in the number of inner core electron shells,so electron shielding increases.

The atomic radius increases.The electrostatic force of attraction between the nucleus and valence shell decreases ,so the enrgy required to overcome the weaker electrostatic forces of attraction between the nucleus and valence shell decreases.

:h::smile:.


That's quite a detailed answer. What exam board are you with if you don't mind me asking. :biggrin:
Original post by High Stakes
That's quite a detailed answer. What exam board are you with if you don't mind me asking. :biggrin:


Edexcel,however I read books from the ocr,edexcel and AQA exam boards !
Original post by Kadak
Hope you dont mind if I reformulate your answer .
Number of core inner electron shells increases.
When you go across a period,the electrons are being removed from the same principal quantum shell,so electron shielding is similar.

The number of protons increase,which increases the electrostati force of attraction between the nucleus and valence shell electrons,so the energy required to overcome this increases.
As you go down a group,the number of protons increase but this is outweighed by the increase in the number of inner core electron shells,so electron shielding increases.

The atomic radius increases.The electrostatic force of attraction between the nucleus and valence shell decreases ,so the enrgy required to overcome the weaker electrostatic forces of attraction between the nucleus and valence shell decreases.

:h::smile:.


Thank you for this, it all makes sense now :smile:

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