Atomic Structure
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Question 1
Which statement is correct about the isotopes of
an element?
They have the same
mass number.
They have the same
number of protons and
neutrons in the nucleus.
They have more
protons than neutrons.
They have the same
electron arrangement or
configuration.
Wrong Answer!
Isotopes are 2 or more atoms of the same element with
different number of neutrons (and therefore different
relative isotope masses). They have the same numbers
of protons and hence the same number of electrons.
Question 2
A chemical element with the symbol X has the
electron arrangement 2,8,6. Which chemical
species is this chemical element most likely to
form?
the ion X3+
the ion X6+
the compound H2X
[2H+X2-]
the compound
XF8[X8+ 8F-]
Wrong Answer!
H2S : [2H+X2-]
Question 3
Which of the following particles contains more
electrons than neutrons?
1
35

39

I. 1 H
II. 17 Cl III. 19 K
I only
II only
I and II only
II and III only
Wrong Answer!
i.
1p
1e
0n
ii. 17p 18e 18n
iii. 19p
18e 20n
Question 4
What information about the structure of a helium
atom can be gained from its emission spectrum?
Most of the mass of the
atom is in its nucleus.
The electrons may exist in
any of several energy levels.
The electrons in the
helium atom are held near
the nucleus.
A helium atom contains two
electrons and two protons.
Wrong Answer!
Emission spectra provide evidence that electrons exist in
fixed energy levels within an atom.
Question 5
What is the correct number of each particle in a
fluoride ion, 19F- ?
Note :
p represents protons; n represents neutrons ; e represents electrons
9p , 10n , 8e
9p , 10n , 9e
9p , 10n , 10e
9p , 19n , 10e
Wrong Answer!
9 protons (from periodic table) ; 10 electrons in the atom
( due to the single negative charge) and 10 neutrons (199)
Question 6
How many valence electrons are present in the
element of atomic number 14?
4
3
2
1
Wrong Answer!
The element is Silicon with the element arrangement
2,8,4
Question 7
Which statement is correct about a line emission
spectrum?
Electrons neither absorb
nor release energy as they
move from low to high
energy levels.
Electrons absorb energy as
they move from high to low
energy levels.
Electrons release energy
as they move from low to
high energy levels.
Electrons release energy as
they move from high to low
energy levels.
Wrong Answer!
Electrons release energy as they move from high to low
energy levels. Light is released.
Question 8
What fraction of a radioisotope will remain after
three half-lives?
1/16
1/3
1/8
3/4
Wrong Answer!
1  ½  ¼  1/8
Question 9
A particular element consists of two isotopes: 72%
of mass number 85 and 28% of mass number
87. What is the expected range of the relative
atomic mass?
Less than 85
Between 85 and 86
Between 86 and 87
More than 88
Wrong Answer!
Relative atomic mass is a weighted average. The more
abundant isotope has a mass number of 85.
72% x 85 + 28% x 87
Question 10
Which is the correct sequence for some of the
various stages that typically occur in the analysis
of an element during mass spectrometry?
Electron bombardment,
vaporization, acceleration,
deflection, detection.
Vaporization, electron
bombardment, deflection,
acceleration, detection.
Vaporization, electron
bombardment, acceleration,
deflection, detection.
Deflection, acceleration,
electron bombardment,
vaporization, detection.
Wrong Answer!
The sample is first vaporized by lowering the surrounding
pressure. A mass spectrometer can only accept gaseous
atoms or molecules. The molecules or atoms are then
subjected to bombardment by high energy electrons
which remove the valence electron to form unipositive
ions. The ions are then accelerated by an electric field
before entering a powerful magnetic field where they
experience deflection according to their mass-to-charge
ratio.
Question 11
The atomic numbers and mass numbers for four
different nuclei are given in the table below.
Which two are isotopes?
Atomic number Mass number
I
II
III
IV
101
102
102
103
258
258
260
259
I and II
II and III
III and IV
I and IV
Wrong Answer!
I.
157 neutrons
II. 156 neutrons
III. 158 neutrons
IV. 156 neutrons
Question 12
Which electronic transition within a hydrogen atom
requires the greatest energy?
n=1n=2
n=2n=3
n=3n=5
n=5n=∞
Wrong Answer!
Energy levels rapidly converge with an increase in n.
Congratulations!
• You have completed the quiz!