Official AQA AS Chemistry Unit 1 - 23Rd May 2013

You can also solve it by algebra in this way, this way does not rely on guesswork but does involves some maths.



Apologies for poor quality!

thanks so much!! what is the definition for hydrogen bonding??

I have a question that I'm pretty sure I asked earlier. How do you draw the structure for metallic and ionic bonding, can someone draw it out for me please ))

thanks so much!! what is the definition for hydrogen bonding??

There was this question in the jan 2012 paper as follows:

The boiling points of fluorine and hydrogen fluoride are –188 oC and 19.5 oC respectively.
Explain, in terms of bonding, why the boiling point of fluorine is very low.

I started to talk about bonding (molecular and ionic) instead of IMF as mark scheme states. I never know when to talk about bonding or IMF in these types of questions. Any help?

Also, I've forgotten how to calculate the RAM in the spectrometry questions. Can anybody outline how you go about doing it from the data given in a table please.

When you heat a substance, you're breaking the intermolecular forces between molecules (hydrogen bonding, dipole-dipole or VDW), you're not changing the bonding of atoms within the molecule.

To find the relative atomic mass, multiply the Mr of each isotope by its relative abundance, add these together and divide it by the total relative abundance

I have a question that I'm pretty sure I asked earlier. How do you draw the structure for metallic and ionic bonding, can someone draw it out for me please ))

I can't physically draw it out as my phone's been sent for repair, so I can't put it up, but I'll upload a few diagrams and try to explain them.

The metallic one (first) is pretty alriight, I'd just draw the ions closer together as if they were touching each other, ane the electrons as 'e-' and more neatly, so the electrons forming a layer to show they're delocalised more clearly. Don't forget, the number of electrons per ion is relative to the charge of the ion.

The ionic one is quite good. You'd need to be able to show it's 3D structure. leave the lines out, but keep the 3D structure, and make it obviously 3D, so draw them out in this kind of arangement.

For each case, minimum of 3x3 ions

Thankyou so much! for metallic do I need to show electrons and will I get penalised if i put wrong number of electrons?

That is just crazy!
My study leave started on the 10th May and ends on the 10th June.

Thankyou so much! for metallic do I need to show electrons and will I get penalised if i put wrong number of electrons?

What is the correct definition of relative atomic mass

It's in the AQA textbook - it can be defined as the average mass per atom relative to the mass of a twelfth (1/12) of a carbon-12 atom

Like Bixel said, you won;t get penalised, but its always better to play it safe.

My textbook says -
the average mass of one atom of an element compared to one twelfth the mass of a carbon 12 atom.
I think thats just the same ?

Like this!

Also when drawing shapes of molecules when I get something like NH2- I show the direction of dative bond and put it in brackets with a minus sign, but never seen marks for this on mark scheme so should I just stop doing that (e.g. in case I get it wrong could I loose marks?).