AS Chemistry- helping each other out!

How do you find out the relative abundance? Anyone? I kind of understand how to for percentage abundance, but not when it's not percentage!!

The question is m/z 113 and m/z 115. the relative atomic mass is 114.5. whats the relative abundance!!!!!!

Write out the spdf notation for aluminium
1s2 2s2 2p6 2s2 2p1
Electron is removed from outside to inside, so third, fourth, 10th 11th and 12th and 13th are removal from s orbital

Al2+(g)->Al3+(g)+e-


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For the second part, as the hydrazine acts as a base, this means it is a proton acceptor (definition), so the N2H4 accepts a H+ ion to form N2H5+.

Not sure how to explain the first part, but the other ion in water is OH-, so I suppose that is what is left when the N2H4 accepts the H+? (sorry for terrible explanation)

I've just done the edexcel January 2012 paper and i'm confused about a couple of questions in the multiple choice, would anyone be able to help me out? (it's question 13)
The ionic radii in nm of some ions are given below
Li+ 0.074
Ca 2+ 0.100
F- 0.133
Cl- 0.180
O2-0.140
S2- 0.185

Which of the following has the most exothermic lattice energy? They all have the same crystal structure
A - LiF
B - LiCl
C - CaO
D - CaS

The answer is C but I don't understand why, is anyone able to explain?
With the second question i'm in the same situation (its part b of this question)

Which of the following compounds will show the greatest difference between the experimental lattice energy and that calculated from a purely ionic model?
A -LiF
B - Li2O
C - CaO
D - CaS

The answer is D

Lattice energy is more exoteric the more charged and smaller the ions are Ca2+ is doubly charged than Li+ and O2- is smaller than S2-

The difference in experimental and theoretical arise from degree if covalency. The bigger the anion the more prone it is to polarisation. S2- has the biggest ionic radius




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Lattice energy is more exoteric the more charged and smaller the ions are Ca2+ is doubly charged than Li+ and O2- is smaller than S2-

The difference in experimental and theoretical arise from degree if covalency. The bigger the anion the more prone it is to polarisation. S2- has the biggest ionic radius




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does anyone know how to answer this question the relative atomic mass of boron is 10.8, in the sample boron exists as two isotopes 10B and 11B. calculate the percentage abundance of 10B in this sample of boron.....PLEASE HELP!!

And ca2+ is smaller

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Hahaha thank you

You're welcome.

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I'm confused, so the paper got leaked and now we have a harder one???

For the fellow edexcel chemistry troopers, what do we think is coming up to torture us with ? I'm absolutely petrified of the exam, considering I have been constantly failing this year -do we keep our heads high and hope the paper is doable? or shall I cry now and not in the exam (as I already did that in maths). The multiple choice is devils spawn and don't get me started on Hess's law, as that is clear nonsense in my brain that cannot fathom the arrows and products at all.

Oh well.

Good luck nonetheless !

For the fellow edexcel chemistry troopers, what do we think is coming up to torture us with ? I'm absolutely petrified of the exam, considering I have been constantly failing this year -do we keep our heads high and hope the paper is doable? or shall I cry now and not in the exam (as I already did that in maths). The multiple choice is devils spawn and don't get me started on Hess's law, as that is clear nonsense in my brain that cannot fathom the arrows and products at all.

Oh well.

Good luck nonetheless !