I'd really appreciate it if someone could post the advantages and disadvantages of Newlands' and Mendeleev's periodic tables. And also same for Bronsted & Lowry, and Arrhenius.

My textbook's really vague.

Reply 64

greenrm

Original post by flumpyfi

Seconded, the answer seems to vary from the cgp to the text book and the aqa spec.

Reply 65

steviep14

Original post by flumpyfi

Newlands':
Adv: First time Elements were grouped together
Grouped in "Law of Octaves" - Every 8th Repeats Properties
Disadv: Ordered by Atomic Weight (RFM)
Only 56 Elements
Properties didn't always match well within groups

Mendeleev's:
Adv: Left Gaps for Undiscovered elements
Disadv: Gaps showed incompleteness and so it wasn't fully trusted immediately

DO NOT MENTION ELECTRONS FOR THIS - THEY DIDN'T KNOW ABOUT THEM

Arrhenius:
Idea that "Acids have Hydrogen ions, Bases have Hydroxide Ions"
Adv: First Acid-Base Theory

Bronsted-Lowry:
Idea that "Proton Donor = Acid, Proton Acceptor = Base"

Basically you don't need Advantages of Acid-Base Theory as such but more the definitions of Acids/Bases

(edited 11 years ago)

Reply 66

AngryBirds4

C3 is much harder!!

You know when water is filtered and purified, is it sedimentation (filters and lime added etc), and then chlorine is added to kill the bacteria?

And can water also be purified by distillation (condensing the steam from water) or by de-ionising everything but H+ and OH-?

Thanks :smile:

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Reply 67

SJWest

Can someone tell me all tests we need to know for Unit 3 chemistry because every past paper i do there is new ones!!!!!

Reply 68

Zoes1234

can someone help and tell me what kind of questions you think we'll get?!

Reply 69

vxrz

Original post by SJWest

Can someone tell me all tests we need to know for Unit 3 chemistry because every past paper i do there is new ones!!!!!

All the ones in the book : NaOH precipitate, flame test, Carbonate test, Nitrates, Sulfates, Ammonia.. Forgotten the rest if there are any left.

Reply 70

steviep14

Original post by AngryBirds4

For "How Britain Cleans Water/Makes it safe" Questions etc.

"Water from Reservoirs enter a Water Treatment plant. It is filtered and mud removed before being passed through several more filters including Fine Sand. Lime is added to remove clumps of dirt. By now the Water looks clean but it is still dangerous. Small quantities of Chlorine are added to destroy bacteria in the water before being stored ready to be pumped to homes"

Distillation is as you say evaporating then condensing but I wouldn't mention it for Cleaning Water
and yes De-Ionisation is removing all ions but H+ and OH-

Your best option is the "Water Treatment Plant" but you can mention De-Ionisation as well.

Reply 71

usycool1

Original post by AngryBirds4

So is that why there's 10 elements per row?

Then why are there several rows if they all have the same number of electrons in the outer shell?

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Ah they don't all have the same number of outer electrons (but it's OK to say this at GCSE to get the mark :smile:

). It's very complicated, but if you would like me to, I can try to explain it (although it may confuse many people) :smile:

Reply 72

AngryBirds4

Original post by usycool1

Ah they don't all have the same number of outer electrons (but it's OK to say this at GCSE to get the mark :smile:

). It's very complicated, but if you would like me to, I can try to explain it (although it may confuse many people) :smile:

Errm, okay.. So if I said the same number of outer electrons and extra electrons between the 2nd and 3rd energy level, I'd get the marks? Sounds good to me :smile:

You could explain if you like, but be prepared if my brain explodes

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Reply 73

HollyD

Hey guys,

I'm feeling pretty good about this, what do u think is gonna come up!??

Reply 74

letsbehonest

I've attached the C3 Jan paper.
All the other papers are quite easy. Getting around the 40s, that one however, I probably just scraped 30s - I havent marked it yet.

AQA-CHY3H-QP-Jan12.pdf529.4KB

Reply 75

username951826

Original post by letsbehonest

I've attached the C3 Jan paper.
All the other papers are quite easy. Getting around the 40s, that one however, I probably just scraped 30s - I havent marked it yet.

my teacher gave our class the Jan 12 CHY3H paper as a mock, it was quite hard,but quite high grade boundaries

Reply 76

letsbehonest

Original post by dtin

my teacher gave our class the Jan 12 CHY3H paper as a mock, it was quite hard,but quite high grade boundaries

I hope we get a straight forward questions. Some calculations and also a description of titration, water cycle, periodic table stuff.

What is 1bii)? evapouration? and what else?

and also the last calculation 5bii) ?
Is 5bi) just asking for a mean? Lol the question is so weird.

Reply 77

letsbehonest

Original post by HollyD

Hey guys,

I'm feeling pretty good about this, what do u think is gonna come up!??

I think they're gonna give us some equations and tell us to say whats happening and I will have no bloody clue -.-

Reply 78

flumpyfi

Original post by steviep14

Thank you so much!

Reply 79

flumpyfi

Original post by letsbehonest

I've attached the C3 Jan paper.
All the other papers are quite easy. Getting around the 40s, that one however, I probably just scraped 30s - I havent marked it yet.