Suggest why the size of atoms increase on going down the group. Here's taking a look at what I wrote:
As we go down the group, the relative radii of the atoms increases. This is because the atoms have more electrons down the group, thus the size of atoms increases.
Why the size of atoms decrease on going across a period.
on going across a period, the relative radii of the atoms of the elements decreases. This is due to the increasing number of protons in the nucleus. Protons make little contribution to the size of atoms, but they increase the positive charge of the nucleus, as a result, drawing the electrons into tighter orbitals. Thus size of atoms decrease on going across a period.
Do these suffice?
Then there's another question
The following results were obtained in experiment on the solubility of sucrose in water performed at T deg cel.
Mass of evaporating dish = 25.0 g
Mass of evaporating dish + saturated solution of sucrose = 200.0g
Mass of evaporating dish + sucrose = 150.0g
From these results (eh, there's also a solubility curve that tells me the solubility of sucrose in 100g of water at different temperatures), work out the value of T.
I only need a rough guide on how to obtain the value of T since I can't provide you guys the graph.
Thanks
For the 1st question, you should include "shielding" or "screening" (ie. due to electron-electron repulsion) effect into your answer. Both down a Group (increasing number of electron shells between the nucleus and valence shell, result in increasing shielding effect), and across a period (approximately same shielding effect since they have same number of inner shell electrons; shielding effect is most significant from inner shell electrons; additional slight shielding effect from increasing valence shell electrons are outweighed by increasing nuclear charge across a period).
As for the solubility question, you probably want to scan and upload a graphic of the actual question including graph, to avoid any misunderstanding of any aspects of the question. Regardless, I'll leave it to others to comment on this question.
Originally posted by Audi:Suggest why the size of atoms increase on going down the group. Here's taking a look at what I wrote:
As we go down the group, the relative radii of the atoms increases. This is because the atoms have more electrons down the group, thus the size of atoms increases.
Why the size of atoms decrease on going across a period.
on going across a period, the relative radii of the atoms of the elements decreases. This is due to the increasing number of protons in the nucleus. Protons make little contribution to the size of atoms, but they increase the positive charge of the nucleus, as a result, drawing the electrons into tighter orbitals. Thus size of atoms decrease on going across a period.
Do these suffice?
Then there's another question
The following results were obtained in experiment on the solubility of sucrose in water performed at T deg cel.
Mass of evaporating dish = 25.0 g
Mass of evaporating dish + saturated solution of sucrose = 200.0g
Mass of evaporating dish + sucrose = 150.0g
From these results (eh, there's also a solubility curve that tells me the solubility of sucrose in 100g of water at different temperatures), work out the value of T.
I only need a rough guide on how to obtain the value of T since I can't provide you guys the graph.
Thanks
I will assume the mass of water to be 50g and amount of sucrose dissolved to be 125g base on what is given. If that is so, 100g of water will dissolve 250g of sucrose so u get the T from that amount.
Originally posted by UltimaOnline:For the 1st question, you should include "shielding" or "screening" (ie. due to electron-electron repulsion) effect into your answer. Both down a Group (increasing number of electron shells between the nucleus and valence shell, result in increasing shielding effect), and across a period (approximately same shielding effect since they have same number of inner shell electrons; shielding effect is most significant from inner shell electrons; additional slight shielding effect from increasing valence shell electrons are outweighed by increasing nuclear charge across a period).
As for the solubility question, you probably want to scan and upload a graphic of the actual question including graph, to avoid any misunderstanding of any aspects of the question. Regardless, I'll leave it to others to comment on this question.
cher, i never hear the word shielding or screening in my chem class b4 sia.
only in phy O.O
Originally posted by yiha093:cher, i never hear the word shielding or screening in my chem class b4 sia.
only in phy O.O
I don't think shielding is in O's Syllabus since i only study that for NMR in uni.
Originally posted by dkcx:I don't think shielding is in O's Syllabus since i only study that for NMR in uni.
That's A lvl Chem...at least that's where I learnt that.
Hallo.
Thanks for helping. I have yet another question of which I'm unsure.
In preparing for C60O3, C60 is dissolved in a solvent at temperatures of 0 degree celsius and below.
What would be a suitable solvent in this case? Not sure of any. If I have to make an "anyhow" guess, it'd be paraffin oil. LOL. or water?(seems more probable)
By the way is C60O3 a simple molecular structure made up of large molecules? If yes, it should have a high melting and boiling point... and perhaps, it can''t conduct electricity?
Never heard of this substance before, so i'm quite curious about it.
Originally posted by SBS2601D:
That's A lvl Chem...at least that's where I learnt that.
I didn't take A's and that info is mainly useful when applied to NMR and maybe some other instrumental usage if not knowing that has little other applications.
Originally posted by Audi:Hallo.
Thanks for helping. I have yet another question of which I'm unsure.
In preparing for C60O3, C60 is dissolved in a solvent at temperatures of 0 degree celsius and below.
What would be a suitable solvent in this case? Not sure of any. If I have to make an "anyhow" guess, it'd be paraffin oil. LOL. or water?(seems more probable)
It can't be water since water becomes ice at 0 and below.
Checking the web, toluene is used for this reaction. If you don't know what toluene is, its just a benzene ring with an additional CH3 group.
Originally posted by Audi:By the way is C60O3 a simple molecular structure made up of large molecules? If yes, it should have a high melting and boiling point... and perhaps, it can''t conduct electricity?
Never heard of this substance before, so i'm quite curious about it.
C60O3 is 1 molecule by itself which is a ball shape with the 'ball' made up of 60 C atoms.
C60s are relatively new in science being discovered about 20+ years ago and research is still being done on their applications etc.
If you are interested in them, feel free to go readup on fullerenes.
Originally posted by Audi:By the way is C60O3 a simple molecular structure made up of large molecules? If yes, it should have a high melting and boiling point... and perhaps, it can''t conduct electricity?
Never heard of this substance before, so i'm quite curious about it.
You mean the buckminsterfullerene?
Originally posted by dkcx:C60O3 is 1 molecule by itself which is a ball shape with the 'ball' made up of 60 C atoms.
C60s are relatively new in science being discovered about 20+ years ago and research is still being done on their applications etc.
If you are interested in them, feel free to go readup on fullerenes.
sec3 eye have.
i believe its actually a simple covalent compound sia. ._.!
Yea. it's in the textbooks already