AS Chemistry- helping each other out!
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Original post by Georgiam247
I have a question on mass spectrometry.
I've read that the technique can be used to determine the structure of an unknown compound but also to identify different isotopes of an element.
If the spectra includes fragments, how are we to know if they are isotopes or just fragments? I'm sure I'm missing something in the mechanism of how this works, I'm having trouble visualising the process as a whole, thank you!!!
I've read that the technique can be used to determine the structure of an unknown compound but also to identify different isotopes of an element.
If the spectra includes fragments, how are we to know if they are isotopes or just fragments? I'm sure I'm missing something in the mechanism of how this works, I'm having trouble visualising the process as a whole, thank you!!!
Is it because you only get fragmentation patterns in molecules? When looking at the spectra of an element you'd only get the isotope spectra cause the element can't be fragmented?
Original post by Georgiam247
Is it because you only get fragmentation patterns in molecules? When looking at the spectra of an element you'd only get the isotope spectra cause the element can't be fragmented?
In the mass spectrometer the molecule is split into fragments and the molecular ion.
Take butane for example CH3CH2CH2CH3 there are two possible ways
CH3CH2CH2CH3----> CH3+ + CH2CH2CH3•
CH3CH2CH2CH3-----> CH2CH3+ + CH2CH3•
Remember that the free radicals are uncharged so don't show up
Posted from TSR Mobile
Chemistry mock next wednesdayyyy!
Haven't studied or done any chemistry for a very long time.
Have started from the start.. Just recapping.
I know this is awful, but I really don't know how to make up an equation.
Like they give you the names of formula's.. say whats reacting with what. But I've realised idk how to write formula's lmfao
help?
Haven't studied or done any chemistry for a very long time.
Have started from the start.. Just recapping.
I know this is awful, but I really don't know how to make up an equation.
Like they give you the names of formula's.. say whats reacting with what. But I've realised idk how to write formula's lmfao
help?
Original post by Dinaa
Chemistry mock next wednesdayyyy!
Haven't studied or done any chemistry for a very long time.
Have started from the start.. Just recapping.
I know this is awful, but I really don't know how to make up an equation.
Like they give you the names of formula's.. say whats reacting with what. But I've realised idk how to write formula's lmfao
help?
Haven't studied or done any chemistry for a very long time.
Have started from the start.. Just recapping.
I know this is awful, but I really don't know how to make up an equation.
Like they give you the names of formula's.. say whats reacting with what. But I've realised idk how to write formula's lmfao
help?
Posted from TSR Mobile
I also have an chemistry exam on Wednesday. Hopefully this link helps
http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_21c/chemical_patterns/elementsrev11.shtml
Do you think you can do well if you cannot even write equations at this latter stage? (Open question).
Original post by Kadak
Posted from TSR Mobile
I also have an chemistry exam on Wednesday. Hopefully this link helps
http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_21c/chemical_patterns/elementsrev11.shtml
Do you think you can do well if you cannot even write equations at this latter stage? (Open question).
I also have an chemistry exam on Wednesday. Hopefully this link helps
http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_21c/chemical_patterns/elementsrev11.shtml
Do you think you can do well if you cannot even write equations at this latter stage? (Open question).
Does anyone know of any good notes on the internet for energetics (hess's law, enthalpy of formation etc)?
Original post by Gladiatorsword
Does anyone know of any good notes on the internet for energetics (hess's law, enthalpy of formation etc)?
I used this website http://chemrevise.org/revision-guides/ to revise for my Chemistry mock which I had today and found to be really useful, I didn't particularly use the energetics revision sheet but I can imagine it is helpful compared to the other stuff I used on there.
Original post by Lollypop0
Im doing OCR 
That's on the website too
Posted from TSR Mobile
Need a little help understanding what happens to the ionic radius going across a period.
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
But then from Si- Cl, the negative: positive charge is greater.. Therefore less attractive?? Idk
Pls help
EDIT:
Oh.. It's just because the number of protons increase across a period? Therefore greater nuclear attraction?
Are ions down a period isoelctronic? Therefore from Na-Cl they are have the same number of electrons?
OK, so if that is the case, then the protons(+) increase, whilst the electrons(-) stay the same. Causing positive>negative, therefore greater nuclear attraction!
(please tell me that is right lmao, and if i've missed any details or whatever
[QUOTE="A;52456081" James="James"]I'm a 2nd year Pharmacy student at uni but I did Edexcel chem for A-levels and got an A.
I'm stronger at organic chemistry than physical/inorganic chemistry it has to be said
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
But then from Si- Cl, the negative: positive charge is greater.. Therefore less attractive?? Idk
Pls help
EDIT:
Oh.. It's just because the number of protons increase across a period? Therefore greater nuclear attraction?
Are ions down a period isoelctronic? Therefore from Na-Cl they are have the same number of electrons?
OK, so if that is the case, then the protons(+) increase, whilst the electrons(-) stay the same. Causing positive>negative, therefore greater nuclear attraction!
(please tell me that is right lmao, and if i've missed any details or whatever
Original post by zhang-liao
Edexcel
[QUOTE="A;52456081" James="James"]I'm a 2nd year Pharmacy student at uni but I did Edexcel chem for A-levels and got an A.
I'm stronger at organic chemistry than physical/inorganic chemistry it has to be said
(edited 9 years ago)
Original post by Dinaa
Need a little help understanding what happens to the ionic radius going across a period.
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
But then from Si- Cl, the negative: positive charge is greater.. Therefore less attractive?? Idk
Pls help
EDIT:
Oh.. It's just because the number of protons increase across a period? Therefore greater nuclear attraction?
Are ions down a period isoelctronic? Therefore from Na-Cl they are have the same number of electrons?
OK, so if that is the case, then the protons(+) increase, whilst the electrons(-) stay the same. Causing positive>negative, therefore greater nuclear attraction!
(please tell me that is right lmao, and if i've missed any details or whatever
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
But then from Si- Cl, the negative: positive charge is greater.. Therefore less attractive?? Idk
Pls help
EDIT:
Oh.. It's just because the number of protons increase across a period? Therefore greater nuclear attraction?
Are ions down a period isoelctronic? Therefore from Na-Cl they are have the same number of electrons?
OK, so if that is the case, then the protons(+) increase, whilst the electrons(-) stay the same. Causing positive>negative, therefore greater nuclear attraction!
(please tell me that is right lmao, and if i've missed any details or whatever
Original post by James A
I'm a 2nd year Pharmacy student at uni but I did Edexcel chem for A-levels and got an A.
I'm stronger at organic chemistry than physical/inorganic chemistry it has to be said
I'm stronger at organic chemistry than physical/inorganic chemistry it has to be said
It decreases across a period. If you go across let's say period 3 you'll see that the number of protons increases, however in terms of electrons they're being added to the same shield so you can say that the shielding remains the same. Because of the bigger nuclear charge and similar shielding, there's a greater electrostatic attraction between positive protons and negative electrons. These electrons are pulled more in towards the nucleus and so reducing the radius.
Hope that helps
Posted from TSR Mobile
(edited 9 years ago)
Original post by Dinaa
Need a little help understanding what happens to the ionic radius going across a period.
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
But then from Si- Cl, the negative
ositive charge is greater.. Therefore less attractive?? Idk
Pls help
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
But then from Si- Cl, the negative
ositive charge is greater.. Therefore less attractive?? Idk Pls help
Why am I quoted but Nvm.*Atomic radius.What's you describe for Na-Al is what should happen for all elements across since the beauty of the periodic table is that it shows trends which hold true for most elements.
Remember, across a period,the electrons are added to the same shell,so electron shielding is similiar and so won't affect the positive charge that much.The increase in protons has is more important across the period than the increase in electrons.
Hope this helps 😃.
Original post by Dinaa
Need a little help understanding what happens to the ionic radius going across a period.
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
But then from Si- Cl, the negative: positive charge is greater.. Therefore less attractive?? Idk
Pls help
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
But then from Si- Cl, the negative: positive charge is greater.. Therefore less attractive?? Idk
Pls help
EDIT:
Oh.. It's just because the number of protons increase across a period? Therefore greater nuclear attraction?
Are ions down a period isoelctronic? Therefore from Na-Cl they are have the same number of electrons?
OK, so if that is the case, then the protons(+) increase, whilst the electrons(-) stay the same. Causing positive>negative, therefore greater nuclear attraction!
(please tell me that is right lmao, and if i've missed any details or whatever
Original post by James A
I'm a 2nd year Pharmacy student at uni but I did Edexcel chem for A-levels and got an A.
I'm stronger at organic chemistry than physical/inorganic chemistry it has to be said
I'm stronger at organic chemistry than physical/inorganic chemistry it has to be said
Posted
(edited 9 years ago)
something confusing me about sterioisomers because my textbook doesnt make it very clear...
With E/Z isomers i get that you compare atomic numbers
My question is do you compare the entire atomic number of the whole group to the other side...or just invidivual atoms...for example
chlorine on one side and CH15(just an example) on the other side
Would you do Chlorine vs Carbon...chlorine wins....then chlorine vs hydrogen...so chlorine vs 15...chlorine wins so chlorine is the highest priority
or would you do chlorine vs the entire atomic number of ch15 which would be like 21...which would be higher than chlorine so CH15 is higher priority
thanks for any help
With E/Z isomers i get that you compare atomic numbers
My question is do you compare the entire atomic number of the whole group to the other side...or just invidivual atoms...for example
chlorine on one side and CH15(just an example) on the other side
Would you do Chlorine vs Carbon...chlorine wins....then chlorine vs hydrogen...so chlorine vs 15...chlorine wins so chlorine is the highest priority
or would you do chlorine vs the entire atomic number of ch15 which would be like 21...which would be higher than chlorine so CH15 is higher priority
thanks for any help
Posted from TSR Mobile
Does anyone know any good websites/materials for isomers of alkenes revision?
Does anyone know any good websites/materials for isomers of alkenes revision?
Original post by Dinaa
Need a little help understanding what happens to the ionic radius going across a period.
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
As you go across the period, the IONIC radii increases because electrons are being added to the same shell so therefore the nuclear charge effect on individual electrons decreases, therefore the IONIC radii increases.
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
Yep, that's pretty much right
But then from Si- Cl, the negative: positive charge is greater.. Therefore less attractive?? Idk
Pls help
I think you're trying to say that as you go across the period from Sillicon to Chlorine, more electrons are being added to the same shell (the 3p shell) so the positive charge on individual electrons is more shared and therefore the ionic radii decreases
EDIT:
Oh.. It's just because the number of protons increase across a period? Therefore greater nuclear attraction?
Yep they do but when you're looking at ionic radii, you tend to look at the shells though and the electrons
For ionisation energy, you look at electron shielding, proton charge (nuclear attraction) and the distance though
Are ions down a period isoelctronic? Therefore from Na-Cl they are have the same number of electrons?
If I remove 1 electron from Na, it is isoelectronic to Ne. If you ADD an electron to Cl so it gains a full electron config so it becomes isoelectronic to Ar
OK, so if that is the case, then the protons(+) increase, whilst the electrons(-) stay the same. Causing positive>negative, therefore greater nuclear attraction!
(please tell me that is right lmao, and if i've missed any details or whatever
Across a period, protons increase and electrons stay on the same shell though (but the electron number DOES however increase). This causes the nuclear attraction to be more equally shared on individual electrons
Original post by Kadak
Chem guide
Original post by 76584
something confusing me about sterioisomers because my textbook doesnt make it very clear...
With E/Z isomers i get that you compare atomic numbers
My question is do you compare the entire atomic number of the whole group to the other side...or just invidivual atoms...for example
chlorine on one side and CH15(just an example) on the other side
Would you do Chlorine vs Carbon...chlorine wins....then chlorine vs hydrogen...so chlorine vs 15...chlorine wins so chlorine is the highest priority
or would you do chlorine vs the entire atomic number of ch15 which would be like 21...which would be higher than chlorine so CH15 is higher priority
thanks for any help
With E/Z isomers i get that you compare atomic numbers
My question is do you compare the entire atomic number of the whole group to the other side...or just invidivual atoms...for example
chlorine on one side and CH15(just an example) on the other side
Would you do Chlorine vs Carbon...chlorine wins....then chlorine vs hydrogen...so chlorine vs 15...chlorine wins so chlorine is the highest priority
or would you do chlorine vs the entire atomic number of ch15 which would be like 21...which would be higher than chlorine so CH15 is higher priority
thanks for any help
bump
Original post by Dinaa
I understand that it increases as you go down a group, because of the increase of protons, therefore extra shells (distance factor) and there is more shielding. But what happens across a period?
I know what happens from e.g. Na- Al. The positive charge increases, therefore positive>negative. Hence, greater attraction between the electrons and the nucleus, making the ionic radius smaller.
(Please tell me if i'm wrong, or if I've missed any details)
But then from Si- Cl, the negative: positive charge is greater.. Therefore less attractive?? Idk
Pls help
EDIT:
Oh.. It's just because the number of protons increase across a period? Therefore greater nuclear attraction?
Are ions down a period isoelctronic? Therefore from Na-Cl they are have the same number of electrons?
OK, so if that is the case, then the protons(+) increase, whilst the electrons(-) stay the same. Causing positive>negative, therefore greater nuclear attraction!
(please tell me that is right lmao, and if i've missed any details or whatever
I was gonna add something but the people who replied earlier gave you some good responses
Complete combustion of 50 cm3 of a hydrocarbon vapour gave 350 cm3 of carbon dioxide?
both gas volumes being measured at the same temperature and pressure. The
formula of the hydrocarbon could be:
A: C8H18
B: C7H16
C: C6H14
D: C5H12
Could some one explain the answer?
I went with my gut instinct and divided 350 by 50. This gave me 7 so I went with B, the answer is correct but I do not understand why???? Has this got something to do with Avogadro??
please help
both gas volumes being measured at the same temperature and pressure. The
formula of the hydrocarbon could be:
A: C8H18
B: C7H16
C: C6H14
D: C5H12
Could some one explain the answer?
I went with my gut instinct and divided 350 by 50. This gave me 7 so I went with B, the answer is correct but I do not understand why???? Has this got something to do with Avogadro??
please help
Original post by TheonlyMrsHolmes
Complete combustion of 50 cm3 of a hydrocarbon vapour gave 350 cm3 of carbon dioxide?
both gas volumes being measured at the same temperature and pressure. The
formula of the hydrocarbon could be:
A: C8H18
B: C7H16
C: C6H14
D: C5H12
Could some one explain the answer?
I went with my gut instinct and divided 350 by 50. This gave me 7 so I went with B, the answer is correct but I do not understand why???? Has this got something to do with Avogadro??
please help
both gas volumes being measured at the same temperature and pressure. The
formula of the hydrocarbon could be:
A: C8H18
B: C7H16
C: C6H14
D: C5H12
Could some one explain the answer?
I went with my gut instinct and divided 350 by 50. This gave me 7 so I went with B, the answer is correct but I do not understand why???? Has this got something to do with Avogadro??
please help
see your post thread in the forum ..
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