Raza10101
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Whats the difference between nucleophilic substitution reactions, elimination reactions and electrophilic reactions?

and can someone please help me understand the term polarisation, and what it means for an element or bond to be polarised, the difference between polar and non-polar bonds?

and can someone please tell me the elements which deviate from the trends in group 2 and period 3 of the periodic table in terms of ionisation energies?

i lost my AS level chemistry book so really need to know the answers to these,

thanks
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Motorbiker
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(Original post by Raza10101)
Whats the difference between nucleophilic substitution reactions, elimination reactions and electrophilic reactions?

and can someone please help me understand the term polarisation, and what it means for an element or bond to be polarised, the difference between polar and non-polar bonds?

and can someone please tell me the elements which deviate from the trends in group 2 and period 3 of the periodic table in terms of ionisation energies?

i lost my AS level chemistry book so really need to know the answers to these,

thanks

Moved this to chemistry study help for you.


I'll answer the polarisation one.

That's when the electron density of the bond or molecule (Not atom) is distorted. If you have a bond between 2 oxygen atoms they have the same electronegativity so it's non polar. Whereas in HF, fluorine is more electronegative so the bond is polar.
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Raza10101
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(Original post by Motorbiker)
Moved this to chemistry study help for you.


I'll answer the polarisation one.

That's when the electron density of the bond or molecule (Not atom) is distorted. If you have a bond between 2 oxygen atoms they have the same electronegativity so it's non polar. Whereas in HF, fluorine is more electronegative so the bond is polar.
yh i kinda get that. The fact that the more electronegative element withdraws electron density from the S+ atom (delta positive).

but i really need to know which elements deviate from the trends in period 2 and group 2' and a possible explanation for why they do it.

thanks alot thoug buddy,
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Motorbiker
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(Original post by Raza10101)
yh i kinda get that. The fact that the more electronegative element withdraws electron density from the S+ atom (delta positive).

but i really need to know which elements deviate from the trends in period 2 and group 2' and a possible explanation for why they do it.

thanks alot thoug buddy,

Yea, that's right.

Which trends are you talking about specifically?
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Raza10101
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(Original post by Motorbiker)
Yea, that's right.

Which trends are you talking about specifically?
Ionisation energies
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Motorbiker
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(Original post by Raza10101)
Ionisation energies

Describe what the current trend is and your understanding for why it exists.

(I'm in teacher mode)
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Raza10101
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(Original post by Motorbiker)
Describe what the current trend is and your understanding for why it exists.

(I'm in teacher mode)
So you want my opinion for the deviation of the trend?

Umm i know magnesium amd aluminium deviate from the trend..probably because of the way the subshells are arranged and maybe because the outer electrons move between a diffrent subshell due to loss of electrons by ionisation...
thats what i understand from it but thats not what the mark scheme says (which i also cant understand)
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Motorbiker
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(Original post by Raza10101)
So you want my opinion for the deviation of the trend?

Umm i know magnesium amd aluminium deviate from the trend..probably because of the way the subshells are arranged and maybe because the outer electrons move between a diffrent subshell due to loss of electrons by ionisation...
thats what i understand from it but thats not what the mark scheme says (which i also cant understand)
What does the mark scheme say?


(I'm actually blanking on this trend even though i just graduated with a first in Master in chemistry so i'm just guiding you along atm)
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Raza10101
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(Original post by Motorbiker)
What does the mark scheme say?


(I'm actually blanking on this trend even though i just graduated with a first in Master in chemistry so i'm just guiding you along atm)
Cant remember it off the top of my head but it says its because the outer electron is in the P subshell instead of the S subshell so when an electron is removed it loses its outer subshell. But how does that affect ionisation energy?
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Motorbiker
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(Original post by Raza10101)
Cant remember it off the top of my head but it says its because the outer electron is in the P subshell instead of the S subshell so when an electron is removed it loses its outer subshell. But how does that affect ionisation energy?
Check out this. http://www.chemguide.co.uk/atoms/properties/ies.html
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Raza10101
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Thanks
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