chemistry unit 1

chapter 1--atomic structure

exam style question--answers

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AS Chemistry Chapter 1
Extension
Answers to teacher notes questions
examination-style
Answers Marks Examiner's tips
1 (a) a
toms with the same number of protons and 1
different number of neutrons
(b) 37
17
Cl 2 There have been a few questions like
this over the years. It's just getting
your head around the numbers ­ then
it's just a bit of arithmetic.
(c) (i) 2s22p63s23p63d104s24p2 1 You really need to know the order of
filling up the sub-levels.
(70 × 24.4) + (72 × 32.4) + (74 × 43.2)
(ii) Ar =
100
= 72.4
(iii)magnetic field / electric field 1 Learn this topic well.
correct link between deflection and m/z 1
correct link between deflection and field 1
2 (a) Ar = (64 × 0.389) + (66 × 0.278) + (67 × 0.147) 2 % told so divide the abundance by
+ (68 × 0.186) 100
= 65.7
zinc / Zn 1
Keep going even if you think you are
not getting the maths right. You may
pick up method marks on the way.
Blank spaces can't score at all!
(b) lectron gun fires high-energy electrons
e 1 Mass spectrometer ­ learn well.
knocks off e­ from Q 1
reasons:
to allow ions to be:
­ accelerated by an electric field 1
­ deflected by a magnet / magnetic field 1
­ detected by current formed at the detector 1
3 (a) relative charge = ­1 2 Don't forget the minus sign for the
relative mass 1/1800 / zero / negligible charge on the electron.
(b) (i) protons = 24 The number of neutrons is the mass
(ii) neutrons = 28 number ­ atomic number.
(iii)abundance or peak height or intensity 3
(c) (i) r eason 1: to allow particles to be The work on mass spectrometer
accelerated / deflected needs to be well understood.
reason 2: generate a current in the detector
(ii) m
agnetic field or electric field or
electromagnet
(iii)deflection depends on mass or m/z 4
AQA Chemistry AS Level © Nelson Thornes Ltd 2008

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AS Chemistry Chapter 1
Extension
Answers to teacher notes questions
examination-style
Answers Marks Examiner's tips
4 (a) (i) a toms with the same number of Always learn definitions. Then they are
protons and with different numbers of `easy' marks.
neutrons
(ii) isotopes have the same electron 3
configuration
(b) 1s22s22p63s1 1 This asks for all sub-levels, so don't use
the abbreviated form using [Ne].…read more

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AS Chemistry Chapter 1
Extension
Answers to teacher notes questions
examination-style
Answers Marks Examiner's tips
(b) (54 × 5.8) + (56 × 91.6) + (57 × 2.6) 2 % told so divide the abundance by 100.
100
= 55.9
(c) (i) 1s22s22p63s23p63d6 1 You really need to know the order of
filling up the sub-levels.…read more

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