1 Principles of chemistry 1
Particles
Question
1 a)
b) i)
ii)
iii)
c)
Answers and guidance
The particles have a fixed pattern or arrangement.
The particles are not free to move.
Marks
1
1
The liquid is now purple.
The colour is evenly spread throughout the test tube
1
1
The crystal particles have separated from
each other and spread evenly
in between the water particles.
1
1
1
Diffusion
The original crystal must contain enough particles to colour the
10 cm3 of water/the repeated dilutions show that there are very
many particles in each 1 cm3 of solution.
To keep the colour after four dilutions means that the crystal must
contain a very large number of particles.
As the crystal was very small, and produces a lot of particles, the
particles must be very small.
1
1
Total
Question
2 a)
1
1
11
Answers and guidance
Box 1
Marks
1
b)
Box 2
1
c)
Box 3
1
Total
Question
3 a)
b)
3
Answers and guidance
33 g/100 g of water
Marks
1
A
1
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c)
Measure 100 g of water into a beaker.
1
Take the water’s temperature.
1
Weigh out 100 g of sodium chloride.
1
Add sodium chloride one spatula at a time until no more will dissolve.
1
Re-weigh the sodium chloride to find the mass of sodium chloride used.
1
Repeat at several different temperatures of water.
1
Total
8
Separating substances
Question
4 a)
Answers and guidance
The particles have no fixed pattern or arrangement.
They are moving quickly.
They are widely separated.
Marks
1
1
1
b)
The particles have no fixed pattern or arrangement.
The particles are touching each other.
The particles are free to move.
The particles have less energy than at point A (in a gas).
1
1
1
1
c)
The particles cannot move; they can only vibrate.
The particles are in a fixed arrangement.
The particles have little energy.
1
1
1
Total
Question
5 a) i)
ii)
b)
10
Answers and guidance
4
Marks
1
23 cm
1
Pigment
Distance pigment
has travelled / cm
R f value of pigment
A
19
B
15
C
9
D
4
0.83
0.65
0.39
0.17
3
1 mark per correct column
c)
Ford, Toyota and BMW have blue paints with Rf value of 0.83.
BMW and Hyundai have Rf value of 0.39 for yellow paint.
So, the missing car must be made by BMW.
Total
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1
1
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1 Principles of chemistry 1
Atomic structure
Question
6a) i)
ii)
iii)
b) i)
ii)
c) i)
ii)
Answers and guidance
19
The number of neutrons is 20.
Mass number is 39.
Add together the protons and the neutrons.
Marks
1
1
1
1
2,8,8,1
Group 1
Rubidium, caesium or francium
One
Elements in the same group of the Periodic Table have the same number
of outer electrons.
1
1
1
1
1
Total
Question
7 a)
9
Answers and guidance
1 mark for each correct row:
Name
Mass number
Marks
4
Number of
Protons
Neutrons
Electrons
fluorine
19
9
10
9
Outer
Electrons
7
chlorine
35
17
18
17
7
bromine
80
35
45
35
7
iodine
127
53
74
53
7
chlorine
37
17
20
17
7
b) i)
ii)
iii)
2,7
1
7
1
Elements in the same group of the Periodic Table have the same number 1
of outer electrons.
c) i)
For 1 mark: they have different numbers of neutrons.
For 2 marks: chlorine-35 has 18 neutrons and chlorine-37 has 20
neutrons.
2
ii)
d)
Isotopes
1
1
1
(𝟑𝟑 ×𝟑)+(𝟑𝟑 ×𝟏)
= 35.5
𝟒
=
Total
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𝟒
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1 Principles of chemistry 1
Question Answers and guidance
Atoms of the same element with different masses / numbers of neutrons.
8 a)
Marks
1
b)
Potassium-41 has two more neutrons than potassium-39.
1
c)
They both have the same number of protons.
1
d)
Total
Question
9 a)
b)
c)
d)
e)
39 × 93 = 3627
41 × 7= 287
287 + 3627 = 3914
𝟑𝟑𝟑𝟑
– 39.1 (rounded)
𝟏𝟏𝟏
1
1
1
1
7
Answers and guidance
Any Group 4 element, e.g. carbon or silicon.
Marks
1
Strontium, barium or radium
Phosphorus
Argon has a full outer shell of electrons.
A calcium ion has lost the two outer electrons.
The ion has got 18 electrons, which is the same number of electrons as
argon.
1
1
1
1
1
Total
Question
10
6
Answers and guidance
1 mark for each correct complete row:
Element
Proton
Electronic
Electronic
Number of outer
number
configuration of an
configuration of an ion
electrons
Marks
5
atom
neon
10
2,8
No ions
8
beryllium
4
2,2
2
2
nitrogen
7
2,5
2,8
5
aluminium
13
2,8,3
2,8
3
phosphorus
15
2,8,5
2,8,8
5
Total
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1 Principles of chemistry 1
The Periodic Table
Question
11 a)
b)
c)
d) i)
ii)
iii)
iv)
Answers and guidance
The pH decreases across the
period.
pH starts high/alkali for
metals.
pH is lower/acid for non-metals.
They are insoluble.
Dissolve the oxide in water.
If it has a pH of less than 7, it is a non-metal oxide
Marks
1
1
1
1
1
1
2 or 3
2 or 3
14
8–14 OR it may not dissolve
1
1
1
1
Total
Question
12 a)
b)
c)
d)
10
Answers and guidance
S and R
W and Q or S and T
S and R
S and R
Elements in the same group always have the same number of outer
electrons.
Marks
1
1
1
1
1
S = 2,2
P = 2,8,4
T = 2,8
1
1
1
f)
g)
Total
Iron
Au
1
1
10
Question
13 a) i)
Answers and guidance
Marks
1
e)
Magnesium
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ii)
Calcium
b)
They both have two outer electrons.
Elements with the same number of outer electrons are in the same
group.
1
1
c)
Magnesium has (two) outer electrons it can lose.
Argon has no outer electrons/has a full outer electron shell.
1
1
1
d)
Barium
1
Krypton
Total
Question
14 a)
b)
c)
d)
8
Answers and guidance
N and L
K
−1
M
It is a noble gas / it has a full outer electron shell.
Total
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Marks
1
1
1
1
1
5
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1 Principles of chemistry 1
Question
15 a)
b)
c)
d)
e)
f)
Answers and guidance
A, B or D
A
D
C and E
2,8,6
Oxygen
Total
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Marks
1
1
1
1
1
1
6
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