Advanced Higher Chemistry 2012-2013

emma_1995

Just going through the past papers by unit by year that our teacher gave us. It's unbelievable how many multi-choice questions are just straight repeats!

Oh that's a good idea to go through it unit by unit. I'm going to make sure I understand all the multiple choice then if they repeat themselves :smile:

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Reply 581

Bonzo10

Original post by emma_1995

Oh that's a good idea to go through it unit by unit. I'm going to make sure I understand all the multiple choice then if they repeat themselves :smile:

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It's not EVERY question, and I've only been focusing on unit 3 today, so can't speak for units 1 and 2. Have a look through questions 25-40 (roughly) of the multi-choice for the past ten years. You'll see a few repeats.

Reply 582

deedee123

16

Original post by I am Ace

So what is covalent character?
I know (think) that ionic character is how electronegative and if it conducts when in solution/ molten.

I think it is just how low the electronegativity is-the opposite of ionic character.

Reply 583

I am Ace

4

Original post by deedee123

I think it is just how low the electronegativity is-the opposite of ionic character.

Yea, you must be right :smile:

Reply 584

I am Ace

4

Original post by deedee123

I think it is just how low the electronegativity is-the opposite of ionic character.

Original post by Bonzo10

It's not EVERY question, and I've only been focusing on unit 3 today, so can't speak for units 1 and 2. Have a look through questions 25-40 (roughly) of the multi-choice for the past ten years. You'll see a few repeats.

I just remembered Khan academy has an organic chemistry playlist!
https://www.youtube.com/watch?v=X-VCk3WrGlM&list=EC7305D1BC80498DA6

Reply 585

I am Ace

4

Why does the shape go from trigonal planar to tetrahedral?

BF 3 + F - --> BF 4 -

Reply 586

Asklepios

19

Original post by I am Ace

Why does the shape go from trigonal planar to tetrahedral?

BF 3 + F - --> BF 4 -

In BF3
Boron has 3 bonding electrons
Each fluorine has 1 = 3 electrons
=> In total = 6e = 3 pairs (all bonding, no lone pairs)

In terms of VSEPR structures, 3 pairs means a trigonal planar shape

In BF4
Boron has 3 bonding electrons
Each fluorine has 1 = 4 electrons
Overall 1- charge = 1 electron
=> In total = 8e = 4 pairs (all bonding, no lone pairs)

This is tetrahedral

Reply 587

I am Ace

4

What's VSEPR?
Ah so for BF4 the other electron comes from the Fluorine (a dative covalent bond)?

Reply 588

Asklepios

19

Original post by I am Ace

What's VSEPR?
Ah so for BF4 the other electron comes from the Fluorine (a dative covalent bond)?

Valence shell electron pair repulsion

Reply 589

I am Ace

4

Original post by Asklepios

Valence shell electron pair repulsion

Had a look, slowly starting to get it, I'm going to try some questions in that link (question bank) you suggested for someone else.
Although, just had a look, do tthey have solutions?
This one btw http://www.educationscotland.gov.uk/Images/questions_tcm4-121203.pdf
If not does anybody have a link to unit based past paper questions?

Reply 590

hmz12

good to see everyone helping each other,

I am so ****ed for this hoping for a C
dont need it but yeah

keep 3hunna my fellow chemists

Reply 591

Lala:

Original post by I am Ace

Had a look, slowly starting to get it, I'm going to try some questions in that link (question bank) you suggested for someone else.
Although, just had a look, do tthey have solutions?
This one btw http://www.educationscotland.gov.uk/Images/questions_tcm4-121203.pdf
If not does anybody have a link to unit based past paper questions?

http://www.educationscotland.gov.uk/Images/answers_to_questions_tcm4-117086.doc this is the answers to the additional questions :smile:

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Reply 592

I am Ace

4

Original post by Lala:

http://www.educationscotland.gov.uk/Images/answers_to_questions_tcm4-117086.doc this is the answers to the additional questions :smile:

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You are a top lad!

Reply 593

I am Ace

4

What general trends of the periodic table should we know?
I know you can work them out in the exam, but just so I can write a list and put it on my wall or something

Reply 594

deedee123

16

Original post by I am Ace

What general trends of the periodic table should we know?
I know you can work them out in the exam, but just so I can write a list and put it on my wall or something

the ones from higher, like increasing nuclear charge across a period etc

then all the hydride, oxide & chloride ones- the bonding and structor of them, their acid/base character and their reaction with water.