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OCR AS Chemistry A Unit 1 retake - Friday

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Reply 40

Jono300

I_Need_To_Revise

Thanks a lot

Have you got one for unit 2 by any chance?

Weelll, I have done a Unit 2, section 1 powerpoint so far, which I have attached.

Also, I have attached a very, very brief overview of Unit 2 using the Exam Café CD.

Hope they help! :biggrin:

Basic Concepts and Hydrocarbons (module 1).ppt643.6KB

Chemistry Unit 2 - basic version.ppt57.3KB

Reply 41

786girl

PLEASE CAN SOMEONE CONFIRM
whether we need to know about the scientists that discovered the electron, like rutherford etc...
WHAT IF THEY TEST IT??
:s-smilie:

I DONT KNOW ANYTHING!!!!!!!!!!

Reply 42

Jens of the desert

Could we be asked to explain a trend in melting boiling points down group II as I'm only used to talking about ionisation energy for a question like that (especially because group II only partake in metallic bonding)?

Reply 43

WizKid07

Can someone explain the trends accross a period and down a group.

Reply 44

TwirlGirl

WizKid07

Can someone explain the trends accross a period and down a group.

Atomic radius decreases across a period. Due to increased nuclear charge and electrons being added to the same shell. Hence no extra electron shielding. Electrons are attracted more strongly to the nucleus. First ionisation energy generally increases across a period (obviously the 1st IE for a group 2 element is higher than a group 3 element, though).

Atomic radius increases down a group despite the increase in nuclear charge. Electrons are added to new shells which increases the electron shielding. Electrons further from the nucleus mean that they are less strongly attracted. First ionisation energy decreases down a group.

Reply 45

786girl

Mr van der WAALs

I really hate electronegativity and the trends of the periodic table. Most of the other stuff is pretty basic; the only difference from the old 2811 past papers is the addition of salts.

Hi im going to explain how YOU are formed.

movement of electrons generates an instantaneous dipole

instantaneous dipole induces further dipoles on neighbouring molecules/atoms

attraction between these temporary induced dipoles results in YOU :redface:

...i really hope that was right and i also hope this question comes up its taken me ages to learn it :frown:

Reply 46

TwirlGirl

786girl

...i really hope that was right and i also hope this question comes up its taken me ages to learn it :frown:

Reply 47

INeedToRevise

Jono300

Weelll, I have done a Unit 2, section 1 powerpoint so far, which I have attached.

Also, I have attached a very, very brief overview of Unit 2 using the Exam Café CD.

Hope they help! :biggrin:

thanks a lot :smile:

Reply 48

WizKid07

TwirlGirl

Thanks for that, it was really helpful :smile:

Reply 49

intellectual1

How many past papers are you practicing? All of them from 2000 - 2009? Or are the New Spec papers sufficient to gain a good grade? hmmm

Reply 50

jontylol

Jono300

I've attached a powerpoint of unit 1 - if it's worked.

Hope it helps! :smile:

Thats awesome :biggrin:

Cheers! And you dont happen to have the Unit 2 one do you? That would be great!

edit; never checked page 3 :P Sorry!

Reply 51

TwirlGirl

intellectual1

How many past papers are you practicing? All of them from 2000 - 2009? Or are the New Spec papers sufficient to gain a good grade? hmmm

Not all, but probably about half.
I imagine if you do all the questions in the book and the recent papers then that'd be enough though. (i havent done any qs from the book)

Reply 52

jimber

I don't even have the book! All lent out to current y12s so will probably do 3/4 papers tomorrow

Reply 53

INeedToRevise

Anyone have any predictions on what will come up on friday- "what you should definitely revise because its almost certain it will come up"???
obviously moles :smile:

Reply 54

Dr WestwooDD

I_Need_To_Revise

Anyone have any predictions on what will come up on friday- "what you should definitely revise because its almost certain it will come up"???
obviously moles :smile:

Shapes and bond angles; ionisation energies and periodic trends; isotope/relative atomic mass definition; maybe hydrogen bonds (water) and anyalmous properties;

I am so bored of this module now; its sooooo boring compared to the other units :eek3:

Reply 55

INeedToRevise

Can someone explain please:
Why do the group 2 elements increase in reactivity as you go down the group?
And why do the melting points and boiling points decrease down the group?

:smile:

Reply 56

INeedToRevise

Mr van der WAALs

i prefer this unit to unit 2- i cant remember anything in unit 2 :s-smilie:

all of the addition reactions and conditions :eek:

Reply 57

Dr WestwooDD

I_Need_To_Revise

i prefer this unit to unit 2- i cant remember anything in unit 2 :s-smilie:

all of the addition reactions and conditions :eek:

Lol F322 is easy compared to F324; and F321 is soooo boring compared to F325!! :smile:

Reply 58

TwirlGirl

Mr van der WAALs

Lol F322 is easy compared to F324; and F321 is soooo boring* compared to F325!! :smile:

Nonono...F321 is soooo easy* compared to F325! I haaate F325 - how is it interesting?! And i hate that my place at university depends on me getting a good B in it :frown:

Reply 59

Dr WestwooDD

TwirlGirl

Nonono...F321 is soooo easy* compared to F325! I haaate F325 - how is it interesting?! And i hate that my place at university depends on me getting a good B in it :frown:

Lol F321 is sooo easy; its the first unit after all but F321 is boring as hell; learning about trends and patterns, how dull; F325 is real chemistry. pH, buffers and electrode potentials!! :p: