Download Atoms and isotopes MS

Atomis structure
Atoms and isotopes MS
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1.
(a)
atom of same element/same number of protons but with different
mass number/number
of neutrons;
1
(b)
protons
(c)
/51 nearer to Ar value of 50.94;
1
(d)
carbon, 12/12C;
1
23
electrons
Three correct [2], two correct [1].
23
neutrons
[5]
2.
(i)
2
[1] for number and type of particles and [1] for location.
27
2
(ii)
N2 + 3T2  2NT3;
Correct formulas [1], balancing of correct equation [1].
2Na + 2T2O  2NaOT + T2;
Correct formulas [1], balancing of correct equation [1].
If H is
used instead of T in any of the equations [3 max].
Accept any
other suitable equation for both parts.
4
[6]
3.
(a)
mass/density/for gases: rate of effusion or diffusion/melting point/
boiling point 1
Do not accept mass number.
(b)
if 35Cl = x, then (x = 35.00) + (1 – x) 37.00 = 35.45
Award [1] for set up.
therefore, x = 0.775;
2
35Cl = 77.5% and 37Cl = 22.5%;
(need both for mark);
[3]
4.
(a)
atoms of the same element/same number of protons/same atomic number;
having
different numbers of neutrons/different (mass number);
2
Award only [1] max if reference made to elements but
not atoms.
(b)
relative atomic mass = ;
2
(c)
23 electrons;
26 protons;
30 neutrons;
Award [2] for three correct, [1] for two correct.
2
[6]
5.
(a)
atoms of the same element/same atomic number/same number of protons; different
numbers of neutrons/mass numbers;
2
Award only [1] max if reference made to elements but not atoms.
(b)
relative atomic mass = = 69.8;
–1 (SF) possible (treat 69 and 71 as integers)
1
[3]
6.
(a)
an atom of 79Br
an ion of 81Br–
protons
35
35
;
neutrons
44
46
;
electrons
35
36
;
3
(b)
79
(c)
(i)
2,8,8,2/2.8.8.2;
1
(ii)
CaBr2;
1
Br because Ar is closer to 79/OWTTE;
1
[6]
7.
(i)
number of protons in the nucleus/atom;
Do not accept protons and electrons.
1
(ii)
number of protons and neutrons in the nucleus/atom;
1
[2]