AQA CHEM1: 15th May 2012

They don't. I haven't seen any questions on the current spec where they ask you to draw orbitals.

I'm not talking about drawing orbitals. I'm talking about drawing 3d ionic lattices..here you go http://store.aqa.org.uk/qual/gce/pdf/AQA-CHEM1-W-QP-JUN09.PDF and if you look at the mark scheme, you get a mark for drawing the structure in 3D.

Original post by Philippamalko

you'd draw rows of circles (your positive and negative ions) each with an alternating positive and negative charge. As if you were drawing a 3d cube, but made of circles, and stick a charge in each of them.

so the charges go + - + - + - + -

Fine, I get that, but what I'm having trouble with is actually drawing it in 3D..every time I attempt to draw a cube of circles, I always end up mucking it up. I'm pretty useless at art you see.. :colondollar:

(edited 11 years ago)

Reply 381

. . .

Original post by Mystic Creature

I'm not talking about drawing orbitals. I'm talking about drawing 3d ionic lattices..here you go http://store.aqa.org.uk/qual/gce/pdf/AQA-CHEM1-W-QP-JUN09.PDF and if you look at the mark scheme, you get a mark for drawing the structure in 3D.

Sorry my mistake.

Reply 382

Jambone2

7

Original post by ambrin ox

Im really sorry but i didnt get that about the p orbitals? :/ pls help? :frown:

Alright, due to the repulsion caused by electron pairs in an orbital, electrons first fill up empty orbitals. Only once all the orbitals have at least one electron in do they begin to double up. This explains the drop in ionisation energy between group 5 and 6, because of the repulsion between the two electrons in the p-orbital :wink:

Reply 383

Mystic Creature

Original post by . .

Sorry my mistake.

Ahh okay, but do you have to draw the 'interior' atoms as well, or can we get away with just drawing all of the bonds from the 3 faces we can see (if you get what I mean lol)

Reply 384

joker12345

19

Jan 2012 paper - can someone please explain 2d? (mark meltin point of nitrogen on graph with other group 2 elements on it)

Reply 385

. . .

Original post by Mystic Creature

Ahh okay, but do you have to draw the 'interior' atoms as well, or can we get away with just drawing all of the bonds from the 3 faces we can see (if you get what I mean lol)

Might as well you've got nothing to lose. I'm sure they are not going to penalise you for going into too much detail. :redface:

Reply 386

It'sMeAgain

Original post by joker12345

Jan 2012 paper - can someone please explain 2d? (mark meltin point of nitrogen on graph with other group 2 elements on it)

I just realised that it was a gas and so had a low melting/boiling point (can't remember) but yeah, I wouldn't know how to know other than that. :B

@ below: Thanks, finally understand!

(edited 11 years ago)

Reply 387

. . .

Original post by joker12345

Jan 2012 paper - can someone please explain 2d? (mark meltin point of nitrogen on graph with other group 2 elements on it)

Nitrogen has a molecular structure as it is a non-metal. And molecular structures have low melting points because vdw forces exist between the molecules which don't require a lot of energy to overcome.

Reply 388

It'sMeAgain

How do we know when to mention vdWs? For example, in Jan 11, Q5 (a) 'State the type of structure shown by a crystal of silicon.
Explain why the melting point of silicon is very high.'

I get that we say it is macromolecular with strong covalent bonds and need a lot of energy to break, but if we also say macromolecular so has lots of electrons and strong vdWs too, do we get 0 because mark scheme says "If IMF/H-bonds/Ionic/metallic CE =0/3"?

Reply 389

Madara

Original post by ambrin ox

Im really sorry but i didnt get that about the p orbitals? :/ pls help? :frown:

See the electrons fill up each orbital one at a time singly before they start pairing up as electrons are negatively charged and repel which is why the answer is 7 not 8 and in that sub shell the other 2 orbitals both contain 1 electron each

Reply 390

MustyQ

1

Original post by Philippamalko

It is in group 5, so has 5 outer electrons. so in AsH3 it would be bonded to 3 Hydrogen atoms leaving a lone pair (if you were drawing it)

i understand but 2 + 8 + 8 + 8 + 7 = 33 ?

Reply 391

joker12345

19

could anyone tell me how to do 1b)iv) ?
http://store.aqa.org.uk/qual/gce/pdf/AQA-CHEM1-W-QP-JAN10.PDF

Reply 392

joker12345

19

Also, in hydrogen bonding, do both lone pairs on the Oxygen 'bond' with one of the hydrogens on another oxygen?

Reply 393

username890104

2

Original post by joker12345

could anyone tell me how to do 1b)iv) ?
http://store.aqa.org.uk/qual/gce/pdf/AQA-CHEM1-W-QP-JAN10.PDF

There is no magic number, but it is using knowledge that once Mg has lost 2 electrons it now has a electronic configuration similar to that of a noble gas (full outer shell). The energy required to then remove the next electron is much greater.

Personally, I would've gone with around 7000 kJmol^-1.

Reply 394

username890104

2

Original post by It'sMeAgain

How do we know when to mention vdWs? For example, in Jan 11, Q5 (a) 'State the type of structure shown by a crystal of silicon.
Explain why the melting point of silicon is very high.'

I get that we say it is macromolecular with strong covalent bonds and need a lot of energy to break, but if we also say macromolecular so has lots of electrons and strong vdWs too, do we get 0 because mark scheme says "If IMF/H-bonds/Ionic/metallic CE =0/3"?

You need to mention that it has a macromolecular structure. Many strong covalent bonds. These strong covalent bonds require lots of heat energy to break the bonds to result in melting.

The reason you couldn't mention vdW is because it doesn't have them, but also because it wouldn't actually be a contributing factor when compared with the covalent bonds.

You mention vdW for simple molecules, especially when comparing melting and boiling points of sulfur and phosphorus.

Reply 395

It'sMeAgain

Original post by Tullia

You need to mention that it has a macromolecular structure. Many strong covalent bonds. These strong covalent bonds require lots of heat energy to break the bonds to result in melting.

The reason you couldn't mention vdW is because it doesn't have them, but also because it wouldn't actually be a contributing factor when compared with the covalent bonds.

You mention vdW for simple molecules, especially when comparing melting and boiling points of sulfur and phosphorus.

Ok, thanks a lot =) It was really bothering and I was thinking I'd mess it up in the exam without even knowing it so I really appreciate the explanation and it finally makes sense. ^^ (Though I thought vdW were present in all molecules? Agh, I'm just going to accept it aha)

(edited 11 years ago)

Reply 396

AspiringDoctor

13

Good luck everybody! :smile:

ye good luck :smile:

what do you think will come up?

Reply 399

username854791

14

Guys why is it foundation? what is the difference? I am not doing this board. I actually looked at the papers posted my the OP and was happy that I could do them, then saw that it was foundation. does this mean there is higher. if so then was grades can you get in them?

AQA CHEM1: 15th May 2012

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you