Practice (MCQs)
1. The atomic number of magnesium is 12. When magnesium reacts to form an ionic compound,
the electronic configuration of the magnesium ion formed is
(1980 P1 Q10)
A
B
C
D
E
2, 8
2, 8, 1
2, 8, 2
2, 8, 3
2, 8, 4
(
2. The mass number of an atom is equal to
A
B
C
D
E
)
(1980 P1 Q12)
the number of neutrons in the atom.
the number of protons in the atom.
the number of electrons in the atom.
the sum of the numbers of protons and electrons in the atom.
the sum of the numbers of protons and neutrons in the atom.
(
)
3. The atomic number of calcium is 20. The electronic structure of the calcium ion can be
represented as
(1981 P1 Q2)
A
B
C
D
E
2, 8
2, 8, 4
2, 8, 8
2, 8, 8, 2
2, 8, 8, 4
(
)
4. A sodium atom has mass number 23 and atomic number 11. It follows that the atom contains
(1981 P1 Q4)
A
B
C
D
E
11 electrons.
11 neutrons.
12 protons.
23 neutrons.
23 protons.
(
)
5. Which one of the following sets consists only of the electronic structures of metals?
(1982 P1 Q4)
A
B
C
D
E
2, 8, 3
2, 7
2, 1
2, 5
2
2, 8, 4
2, 8, 7
2, 8, 1
2, 6
2, 8
11 | A t o m i c S t r u c t u r e
2, 8, 5
2, 8, 18, 7
2, 8, 8, 1
2, 7
2, 8, 8
(
)
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6. The symbol for an atom of sodium can be written as
contains
A
B
C
D
E
11 protons and 12 neutrons.
11 neutrons and 12 protons.
12 neutrons and 11 electrons.
11 protons and 12 electrons.
12 protons and 11 electrons.
23
11 Na.
The nucleus of this sodium atom
(1981 P1 Q4)
(
)
7. Which one of the following correctly gives the numbers of the different particles to be found in
an aluminium ion?
(1984 P1 Q4)
protons
A
B
C
D
E
neutrons
10
13
13
13
27
27
14
26
14
13
electrons
13
27
13
10
27
(
)
8. What is the atomic structure of the Z2- ion in which Z has atomic number 8 and mass number
18?
(1985 P1 Q2)
A
B
C
D
E
electrons
8
8
8
10
10
protons
8
8
8
8
8
neutrons
8
10
18
8
10
9. What is the atomic structure of a phosphorus atom?
protons
A
B
C
D
E
neutrons
15
15
16
16
16
12 | A t o m i c S t r u c t u r e
16
16
15
15
16
(
)
(1985 P1 Q6)
electrons
15
16
15
16
15
(
)
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10. The atoms of five elements in the Periodic Table have atomic numbers and mass numbers as
follows:
element
V
W
X
Y
Z
atomic number
4
5
6
7
8
mass number
9
11
12
14
16
Which of the following, A, B, C, D or E represents the number of neutrons in the nucleus of
each of the elements?
(1985 P1 Q6)
A
B
C
D
E
11.
V
W
X
Y
Z
4
5
8
9
13
5
6
10
11
16
6
6
12
12
18
7
7
14
14
21
8
8
16
16
24
(
An element Z exists in three isotopic forms as shown below.
isotope
isotopic abundance
150
Z
50%
155
Z
25%
)
(FHSS Prelim 2016)
157
Z
25%
What is the relative atomic mass of element Z?
A
B
C
D
150
152
153
154
13 | A t o m i c S t r u c t u r e
(
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)
3.
(a)
Complete the following table.
Mass
number
Atomic
number of
elements
sodium atom
23
11
calcium ion
40
Number of
electrons
protons
neutrons
18
chloride ion
17
20
(b)
What name is used to describe atoms which have the same atomic number but
different mass numbers?
(c)
How many electrons, protons and neutrons are present in the hydrogen ion H+?
(June 83)
4.
Use the following information to answer the questions below about the elements A, B, C, D
and E.
element
A
B
C
D
E
atomic
number
mass
number
3
18
8
12
19
7
40
16
24
39
electronic
structure
2, 1
2, 8, 8
2, 6
2, 8, 2
2, 8, 8, 1
(a)
Which element has 22 neutrons in each atom?
(b)
Is the bonding between C and E ionic or covalent?
(c)
Which element is a noble gas?
(d)
Which two elements form ions with the same electronic structure as neon?
(e)
Which two elements are in the same Group of the Periodic Table?
(June 84)
5.
Selecting from the following ions
Ca2+
Cl-
Li+
Na+
O2-
choose the ion that
(i)
has the same arrangement of electrons as neon,
(ii)
has only two electrons
(iii)
has the same arrangement of electrons as Al3+
15 | A t o m i c S t r u c t u r e
(June 87)
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6.
Complete the following table concerning the three types of particles present in atoms.
relative mass
relative charge
position in the atom
neutron
proton
electron
[3]
(Nov. 88)
7.
An atom of an element contains twelve electrons.
(a)
Name this element.
(b)
In which Group of the Periodic Table is this element?
(c)
Give the formula for the ion formed by this element.
[3]
(Nov. 88)
16 | A t o m i c S t r u c t u r e
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