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1.
The following table gives data for some elements:
Element
Aluminium
Bromine
Chlorine
Copper
Helium
Iron
Lead
Magnesium
Mercury
Nitrogen
Oxygen
Phosphorus
Potassium
Sodium
Sulphur
Zinc
M.p. (°C)
660
−7
−101
1083
−270
1540
327
650
−39
−210
−219
44
64
98
119
419
B.p. (°C)
2450
58
−35
2600
−269
2900
1750
1110
357
−196
−183
280
760
890
445
906
Electrical conductivity
good
poor
poor
good
poor
good
good
good
good
poor
poor
poor
good
good
poor
good
Use the table to answer the following questions.
(a) What is the melting point of iron?
(b) Which element melts at −7°C?
(c) Which element boils at 280°C?
(d) Which element has a boiling point only 1°C higher than its melting point?
(e) Over what temperature range is sulphur a liquid?
(f)
Which element has
(i) the highest melting point?
(ii) the lowest melting point?
1
(g) Divide the elements into two groups, metals and non-metals.
(h) List the metals in increasing order of melting points.
(i)
List the elements which are (I) gases (II) liquids (III) solids at room conditions.
[13M]
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2.
The following table gives some physical properties of eight elements.
Element
M.p. (°C)
B.p. (°C)
Electrical conductivity
A
−7
58
non-conductor
B
850
1480
good conductor
C
−39
357
good conductor
D
940
2800
semi-conductor
E
−101
−35
non-conductor
F
113
445
non-conductor
G
232
2687
good conductor
H
−71
−62
non-conductor
(a) Give the physical states of the elements under room conditions.
(b) Which elements are metals?
(c) Which elements are non-metals?
(d) Which element is a semi-metal?
(e) Name elements A and C. Give reasons for your answers.
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3
3.
The diagram below shows the structure of an atom of element X. The crosses,
black dots and white dots represent three different kinds of particles.
(a) Identify these particles and state their charges.
(b) What is the atomic number and mass number of element X?
(c) To which group does element X belong? What name is given to the elements in
this group?
(d) What would be the formula of the compound formed by X and carbon?
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4
4.
Assume the nucleus of a fluorine atom to be a sphere with a radius of 5 × 10 −13
cm and a mass of 3.15 × 10−23 g. Calculate the density of the fluorine nucleus.
(Hint: Volume of a sphere =
4 3
πr )
3
[2M]
5.
Given an element with a full atomic symbol of
23
11 X
.
(a) What is the electronic arrangement of element X?
(b) Determine whether element X is a metal or not.
(c) Calculate the number of
(i)
protons,
(ii) electrons, and
(iii) neutrons in
23
11 X
.
[5M]
5
6.
Oxygen has 3 isotopes,
16
17
8O , 8O
and
18
8 O respectively.
(a) What is the electronic arrangement of oxygen?
(b) Given that the relative atomic mass of oxygen is 16.0044 and the percentage
abundance of
16
8 O is
99.76%. Calculate the percentage abundance of
17
8 O and
18
8 O respectively.
(c) Do the isotopes have the same
(i)
physical properties?
(ii) chemical properties?
Explain briefly.
(d) State one daily use of oxygen.
[10M]
6
7.
Consider an element X, which has 2 isotopes,
75
27 X
and
y
27 X
respectively.
(a) If the percentage abundances of the two isotopes are both 50% while the relative
atomic mass of the element is 77.5. Calculate the value of y.
(b) A certain scientist claimed, ‘I have discovered a third isotope of X,
75
28 Z
.’ State
and explain whether his claim is valid or not.
(c) Does Z have the same chemical properties as X?
(d) Determine the number of neutrons in
75
28 Z
.
[6M]
7
8.
Consider an element Y, which has 2 isotopes,
(a) If the percentage abundances of
63
30Y
and
63
30Y
66
30Y
and
66
30Y
.
are 40% and 60% respectively,
calculate the relative atomic mass of Y.
(b) A student claims, ‘Both isotopes of Y have same physical properties as they
belong to the same element.’ State and explain whether he is correct or not.
(c) Do these two isotopes have the same chemical properties?
(d) Determine the number of
(i)
electrons,
(ii) mass number and
(iii) atomic number for each isotope.
[11M]
8
9.
P
proton
Q
R
S
neutron
The above figure shows the nuclei of four atoms P, Q, R and S.
(a) Which two atoms are isotopes of the same element?
(b) What is the name of the element in (a)?
(c) What are the names of the two isotopes in (a)?
(d) Write the full atomic symbol of each of the atoms P, Q, R and S.
[5M]
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10. The following table gives the atomic numbers of various elements (represented
by letters P, Q, R, S, T and U).
Element
Atomic number
P
3
Q
5
R
11
S
14
T
16
U
20
Using the given information, find out for each element
(a) the number of electrons in an atom.
(b) the electronic arrangement of an atom.
(c) the group it belongs to in the Periodic Table.
(d) whether it is classified as a metal, non-metal, or semi-metal.
[12M]
10
11. Eric was given a sodium sample, an iron nail and a glass trough filled with water
up to one-third full.
(a) He dropped the sodium sample into the trough of water directly by hand. Suggest
a more appropriate approach for this procedure.
(b) State the observations of the reaction between sodium and water.
(c) Then he tested the resultant solution with a piece of red litmus paper. What
would she observe? Explain your answer.
(d) Eric repeated the experiment by dropping an iron nail into the trough of water.
State the observation.
(e) Then he tested the resultant solution with a piece of red litmus paper. What
would she observe?
(f)
Suggest TWO safety precautions of this experiment.
[12M]
11
12. Fluorine, chlorine, bromine, iodine and astatine all belong to Group VII in the
Periodic Table.
(a) What are Group VII elements commonly known as?
(b) State TWO common properties of Group VII elements.
(c) Which of the above elements is the most reactive?
(d) Raymond collected a pale yellow gas sample under room conditions, this gas is
one of the above elements. Suggest what it most likely is.
(e) Write down the electronic arrangement of the element in (d).
(f)
Raymond tried to distinguish the above elements by smelling them directly.
Comment and explain whether his approach was desirable.
[8M]
12
13. The following shows a part of the Periodic Table.
Group
Period
2
3
I
a
b
II
c
d
III
e
f
IV
g
h
V
i
j
VI
k
l
VII
m
n
VIII
o
p
(a) Name the elements a and b.
(b) A compound of b is heated in a non-luminous flame. What would you observe?
(c) Name another metal which also belongs to Group I (except elements a and b).
What are Group I metals also known as?
(d) Explain whether the metal in (c) would be more reactive than elements a and b
or not.
(e) What is element g? Name another element in the above Periodic Table that has
the same number of outermost shell electrons.
[9M]
13
14. Cathy wanted to investigate the action of water on lithium, sodium and
potassium.
(a) Which group do lithium, sodium and potassium belong to?
(b) State ONE common physical property of the above metals.
(c) State the observations for the reaction between lithium and water.
(d) State the observations for the reaction between potassium and water.
(e) If the gas produced in (c) was collected and tested by a burning spirit. What
would happen?
(f)
Cathy wanted to test if caesium reacted similarly with water by dropping a piece
of caesium into water directly. Explain whether she should do that experiment or
not.
[12M]
14
15. The following shows a part of the Periodic Table.
Group
Period
2
3
I
Li
Na
II
Be
Mg
III
B
Al
IV
C
Si
V
N
P
VI
O
S
VII
F
Cl
VIII
Ne
Ar
(a) Which is the least reactive halogen in the above Periodic Table? Suggest one of
its daily uses.
(b) Which of the above elements is used to make transistors?
(c) Which of the elements in the above Periodic Table have the greatest atomic
number? Write down its electronic arrangement.
(d) Maggie claimed that, ‘Lithium and sodium have the same chemical properties as
they belong to the same group.’ Explain whether her claim is correct or not.
(e) Maggie then added a piece of sodium to water. Briefly describe the observations.
(f)
Explain why lithium and fluorine are arranged in the same period in the Periodic
Table. State one similarity between them.
[12M]
15
Answers
1.
(a) 1540°C [1]
(b) Bromine [1]
(c) Phosphorus [1]
(d) Helium [1]
(e) 119 − 445°C [1]
(f)
(i)
Iron [1]
(ii) Helium [1]
(g) Metals: aluminium, copper, iron, lead, magnesium, mercury, potassium, sodium,
zinc [1]
Non-metals: bromine, chlorine, helium, nitrogen, oxygen, phosphorus, sulphur
[1]
(h) Mercury, potassium, sodium, lead, zinc, magnesium, aluminium, copper, iron [1]
(i)
(I)
chlorine, helium, nitrogen, oxygen [1]
(II) bromine, mercury [1]
(III) aluminium, copper, iron, lead, magnesium, phosphorus, potassium, sodium,
sulphur, zinc [1]
2.
(a) Solids: B, D, F, G [1]
Liquids: A, C [1]
Gases: E, H [1]
(b) B, C, G [1]
(c) A, E, F, H [1]
(d) D [1]
(e) A : bromine, the only liquid non-metal; [1] ; C : mercury, the only liquid metal
[1]
3.
(a) Cross: electron, charge: negative (1) [1]
Black dot: neutron, charge: neutral (0) [1]
White dot: proton, charge: positive (+1) [1]
(b) Atomic number = 9 [1]
Mass number = 19 [1]
(c) Group VII; halogens [2]
16
(d) CX4 [1]
4.
density =
=
mass
volume
3.15  10 23
g cm−3 [1]
3
4
 5  10 13
3


= 6 × 1013 g cm−3 [1]
5.
(a) 2,8,1 [1]
(b) X is sodium, which is a metal. [1]
(c) (i)
11 [1]
(ii)
11 [1]
(iii) 12 [1]
6.
(a) 2,6 [1]
(b) Let the percentage abundance of
17
18
8 O and 8 O be
y% and (100 – 99.76 – y )%,
i.e. (0.24 – y)% respectively.
Relative atomic mass of oxygen = weighted average of the relative isotopic
masses
16.0044 =
99.76  16  17 y  18(0.24  y )
[1]
100
y = 0.04 [1]
The percentage of abundance of
17
18
8 O and 8 O are
0.04% [1] and 0.2% [1]
respectively.
(c) (i)
No [1] The isotopes have different masses. [1]
(ii) Yes [1] The isotopes have the same number of electrons. [1]
(d) It could be used to weld and cut metals. [1]
17
7.
(a) 77.5 =
75  50  50 y
[1]
100
y = 80 [1]
(b) His claim is invalid [1] because Z has a different atomic number from X which
makes them different elements. [1]
(c) No [1] (since they are different elements)
(d) Number of neutrons = 75 – 28 = 47 [1]
8.
(a) Relative atomic mass =
40
60
 63 
 66 [1]
100
100
= 64.8 [1]
(b) His claim is incorrect. [1] Isotopes of Y have different physical properties since
they have different masses. [1]
(c) Yes [1]
(d)
63
30Y
66
30Y
: (i) 30 [1]
(ii) 63 [1]
(iii) 30 [1]
: (i) 30 [1]
(ii) 66 [1]
(iii) 30 [1]
9.
(a) P and R [1]
(b) Carbon [1]
(c) P: carbon-13, R: carbon-12 [1]
(d) P:
13
6C
Q:
11
5B
R:
12
6C
S:
13
7N
[2]
10.
(a) P : 3, Q : 5, R : 11, S : 14, T : 16, U : 20 [3]
(b) P : 2, 1; Q : 2, 3; R : 2, 8, 1; S : 2, 8, 4; T : 2, 8, 6; U : 2, 8, 8, 2 [3]
(c) P : I, Q : III, R : I, S : IV, T : VI, U : II [3]
(d) P : metal, Q : semi-metal, R : metal, S : semi-metal, T : non-metal, U : metal [3]
18
11.
(a) He should have gently placed the sample onto the water surface [1] with a pair of
dry forceps. [1]
(b) Sodium melted into a silvery ball [1] which moved about very quickly on the
water surface, [1] producing a hissing sound [1] before finally disappearing
completely. [1]
(c) The red litmus paper turned blue [1] since sodium reacted with water to form an
alkaline solution. [1]
(d) The iron nail sinked to the bottom. [1]
(e) There would be no change. [1]
(f)
Wear safety spectacles [1] and perform this experiment behind a safety screen.
[1]
12.
(a) Halogens [1]
(b) They are reactive [1] and poisonous. [1]
(c) Fluorine [1]
(d) Fluorine [1]
(e) 2,7 [1]
(f)
His approach was undesirable [1] as all halogens are poisonous. [1]
13.
(a) a: Lithium [1]
b: Sodium [1]
(b) It gives a golden yellow flame. [1]
(c) Potassium. [1] Group I metals are also known as alkali metals. [1]
(d) Potassium would be more reactive than lithium and sodium [1] as the reactivity
of Group I metals increases down the group. [1]
(e) Carbon. [1] Silicon also has the same number of outermost shell electrons of
element g. [1]
19
14.
(a) Group I [1]
(b) All are soft metals. [1]
(c) Lithium would float on water, [1] producing gas steadily. [1]
(d) Potassium would melt to a silvery ball [1] which moves about very quickly on
the water surface, [1] producing a hissing sound, [1] burning spontaneously with
a lilac flame [1] before finally disappearing completely. [1]
(e) It would give a ‘pop’ sound. [1]
(f)
She should not do that experiment [1] because the reaction between caesium and
water is explosive. [1]
15.
(a) Chlorine [1] Chlorine is used in the production of bleach. [1]
(b) Silicon [1]
(c) Argon [1]
2,8,8 [1]
(d) Her claim is incorrect. [1] Lithium and sodium have similar but not the same
chemical properties, as they only have the same number of outermost shell
electrons, not the same number of electrons. [1]
(e) Sodium melted into a silvery ball [1] which moved about very quickly on the
water surface, [1] producing a hissing sound [1] before finally disappearing
completely [1].
(f)
They have the same number of electron shells. [1]
20