Chemistry people HELP ME AAAAAAGH!!!!!

[BoffinMum]

I am trying to help DS1 with his iGCSE revision for triple science and we are stuck on these bits of the Chemistry papers:

Valencies
Properties of graphite
Properties of lithium fluoride
Oxidation and reduction
Isotopes

We have a text book here but both of us are more than slightly confused and losing the will to live.

I was rubbish at this in 1984 and even more rubbish now.

HHHHHHEEEEEELP!!!!

While I agree if it is clearly beyond him, the homework needs to go in with best attempts, and if Boffin wants to help her son understand things, where is the problem. Even with the answers given, they will need understanding to get them onto the paper.

So, Boffin

Your Se has 6 electons floating in the outer ring (often in dot and cross diagrams, you only show the outer ring, but if DS is struggling with the concept, I suggest he draws it all out). If gets complicated now. I sugest he stops!
BUT, 2 are in a s shell, which can only hold 2 electrons. The other 4 are in p shell, whic can hold 6, so isn't full.

In the interests of having full levels as an ideal, and full shells if not, the Se would like to gain 2 electrons, or loose 4.
Cl would like to gain an electron.
So, if you get one Se and 4 Cl together, the electrons can jump about. If you do dots as the Se electrons, and X as the Cl electrons, you can then draw an extra DOT on each Cl to make a full shell, and leave the Se with only 30 electrons.

Confused? Leave it, this is at the complicated end of dot and cross ('cause the levels don't all fill up in the right order either, and the 4th level of electrons fills before some of the third level)

A1: the outer shell is full with electrons, so losing or gaining electrons is not advantageous. (You have a noble gas)

A2: Gaining electons to achieve a full outer shell gives a negative charge. Loosing electrons to achieve a full outer shell gives a positive charge. All atoms would like to react with something to achieve a full out shell but loosing or gaining a small number of electrons (i.e. something with one missing electron in the outer shell won;t loose 7 electons to get a full out shell, it will gain one; it is too costly in terms of energy to loose the 7).

A3: N2, O2 and F2 spring to mind?

Info to go with nextphase's response:

OIL RIG ( Oxidation Is Loss of electrons)( Reduction Is Gain of electrons)

B: does he know what an amphoteric hydroxide is??
It can act as an acid or a base, under the right conditions.

Think Aluminium Hydroxide is amphoteric, lead and zinc might also be??? (water also can act as an acid or a base, but that doesn't answer the question, as its not a metal hydroxide)

Be Sulphate + NaOH, will react to form sodium sulphate and Beryllium Hydroxide, which you have been told is a white solid. I'd hazard a guess that a white solid will precipitate out of solution.

C

You've already been given some help in part A.
Li forms 1+ ions, F forms 1- ions, so yes, LiF is balanced.

N likes to be 3-, and as above F 1-. you therefore need NF3 to get anywhere close to keeping all elements happy.

Look up differences between ionic and covalent reactions, or metal and non metal fluorides.

I'd go with metallic and non metallic fluorides! But he's got the idea right!

C3: HINT - one of the fluorides has ionic bonds and the other has covalent bonds (does that help?)

crossed posts nextphase

What we are doing is sticking coloured Post Its on the bits that he simply hasn't got, or where his confidence in the knowledge is extremely shaky, and a larger Post It with a summary of what he is struggling with on the front of each section - Physics, Chemistry, Biology.

Apparently the school has dished this pack of photocopied papers out to every single kids doing iGCSE Science. Set 1 have covered more of the ground, he is in Set 2 and it is not clear to me exactly what he is supposed to have covered and what he hasn't.

There is an A4 sheet with the pack suggesting they look stuff up if they don't know it, or read their iGCSE text books and work it out. This seems to rely on the fact that parents are knowledgeable enough to be able to answer any of the kids' questions. I am able to do this with Biology but not at all with Chemistry and Physics (I have never even studied Physics apart from one term at school). I even sent DS1 on a residential revision course during the summer holidays but despite him apparently having tried hard while he was there, he's stumped a lot of the time.

I have to say I would not have done this sort of thing as a classroom Music teacher - I mean you could give out a booklet on set works or whatever, but my feeling is that you need to write a mini revision guide of your own with teaching information in there in order for the kids to make proper progress. As it is, DS1 is pretty demoralised by the number of questions he has had to leave blank and frankly I would be in his shoes.

Anyway, we are soldiering on because I'd like him to learn that even if the task is too hard it is possible to chip off bits of it and end up further on than if you had just folded your arms and refused to do it. So we are really grateful for your help.

BlackMogul, no it's not cheating at all. It really is research (and a bit of backfill where I think he hasn't been taught in the right way if I am utterly honest).

PS Frankly it's not doing me any hard exercising my brain muscles on all this either and it is quite satisfying when I actually get the concepts. I wish I had had you lot in 1984 when I was doing my OL Chemistry exam - I spent the whole course in a haze of confusion, as I recall.

harm

A question:

You talk about atoms wanting to gain electrons - how do they know when they are 'full' or what constitutes 'full'?

Electron shells

en.m.wikipedia.org/wiki/Electron_shell

That's an interesting link.

1. How would you see this happen? Electron microscope?
2. Why is the pattern repeated so neatly in this way in the electron shells?
3. Is is string theory where they suggest it's bits of wibbly wobbly stuff inside the electrons that make them want to orbit in the first place?

This is assessment. It's assessing his understanding, which seems limited. This is all yr10 stuff, he should be able to do it. If he can't, the paper should reflect that so the teacher isn't under any false impressions.

He should be able to use his text book and gcse bitesize himself by now. There are some fab YouTube channels full of helpful videos. I'll come back tonight with links if you like, but I'm off out now.

He does have a statement of SEN, so working independently is more of a challenge for him than the average 15 year old.

Still, it's a skill that must be learned for the exams and for any further study. Good luck, perhaps start earlier in the holidays next time.

Regaining, I don't need preaching from you. I asked for help with the technical aspects of chemistry, not a lecture on how to approach homework. I am a qualified teacher and I have a PhD in Education so I think I am perfectly capable of working that out for myself. There were particular reasons DS1 wasn't able to tackle the booklet until a couple of weeks before the end of the holidays, largely to do with attending three weeks of other educationally-orientated activities. And you haven't read the thread properly. He has SEN. He has marked up the past papers with post it notes detailing where he is stuck and where he hasn't fully understood the topic. So nobody is feigning understanding here. If YouTube videos worked for him, or sitting in his bedroom alone plodding through the papers worked for him, I am sure we would all be doing that instead of busting a gut trying to scaffold his learning properly for him when we could be out in the garden.

Dude, it was hardly a lecture. I offered technical help and practical advice. Your qualifications weren't clear in any post.

Please don't disregard some of the YouTube videos, there's some absolute gold out there (amid the tripe). Using video is a really helpful way of learning for some students.

I know you probably don't want to hear any more from me, but do look at www.my-gcsescience.com (designed for AQA, but relevant), and the Khan Academy bits are good for maths and higher level sciences.

Just trying to help. I don't think I've said anything mean or unnecessary.