Uddingston Grammar School
CfE Higher Chemistry
Unit 1: Chemical Changes and Structure
Sub-Topic B: Periodicity
Homework 3: Periodicity
1. The spike graph shows the variation in successive ionisation energies of
an element, Z.
In which group of the Periodic Table is element Z?
A
1
B
3
C
4
D
6
2. Which of the following elements has the greatest attraction for bonding
electrons?
A
B
C
D
Potassium
Fluorine
Sodium
Iodine
3. A potassium atom is larger than a sodium atom because potassium has
A
B
C
D
a larger nuclear charge
a larger nucleus
more occupied energy levels
a smaller ionisation energy
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4. Which of the following statements is true?
A
B
C
D
The potassium ion is larger than the potassium atom
The chloride ion is smaller than the chlorine atom
The sodium atom is larger than the sodium ion
The oxygen atom is larger than the oxide ion
5. In which of the following molecules will the chlorine atom carry a partial
positive charge (
A
B
C
D
)?
Cl−Br
Cl−Cl
Cl−F
Cl−I
6. Atoms of nitrogen and element X form a bond in which the electrons are
shared equally. Element X could be
A
B
C
D
carbon
oxygen
chlorine
phosphorus
7. A positively charged particle with electron arrangement 2, 8 could be
A
B
C
D
a neon atom
a fluoride ion
a sodium atom
an aluminium ion
8. Which of the following elements would require the most energy to
convert one mole of gaseous atoms into gaseous ions each carrying two
positive charges?
(You may wish to use the data booklet.)
A
B
C
D
Scandium
Titanium
Vanadium
Chromium
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9. Which of the following elements has the least attraction for bonding
electrons?
A
B
C
D
Caesium
Oxygen
Fluorine
Iodine
10. Which of the following equations represents the first ionisation energy
of chlorine?
A
B
C
D
Cl–(g) 2Cl(g) + 2e–
Cl–(g)  Cl2(g) + 2e–
Cl(g)  Cl+(g) + e–
Cl2(g)  2Cl+(g) + 2e–
11. A metal (melting point 328oC, density 11.3 gcm-3) was obtained by
electrolysis of its molten chloride melting point melting point 501oC,
density 5.84 gcm-3 ).
During the electrolysis, how would the metal occur?
A
as a solid on the surface of the electrolyte
B
as a liquid on the surface of the electrolyte
C
a solid at the bottom of the electrolyte
D
a liquid at the bottom of the electrolyte
12. Which of the following reactions refers to the third ionisation energy of
sodium?
A
B
C
D
Na(s) → Na3+(g) + 3e–
Na(g) → Na3+(g) + 3e–
Na2+(g) → Na3+(g) + e–
Na3+(g) → Na4+(g) + e–
13. Many patterns in the physical and chemical properties of elements are
observed.
(a) Why does the electronegativity of elements increase across the
second row of the Periodic Table from lithium to fluorine?
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(b) The Periodic Table groups together elements with similar properties.
In most Periodic Tables hydrogen is placed at the top of Group 1, but
on some it is placed at the top of Group 7.
Using your knowledge of Chemistry, comment on why hydrogen can be
placed in both Group 1 and Group 7.
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14. Common salt, NaCl, is widely used in the food industry as a preservative
and flavour enhancer.
(a) Write the ion-electron equation for the first ionisation energy of
sodium.
1
(b ) Explain clearly why the first ionisation energy of sodium is much
lower than its second ionisation energy.
3
15.
(a) Atoms of different elements are different sizes. What is the
trend in atomic size across the period from sodium to argon?
1
(b) Atoms of different elements have different ionisation energies.
Explain clearly why the first ionisation energy of potassium is less
than the first ionisation energy of sodium.
1
(c) Look at the table below. Why is there a large increase in ionic radius
on going from Si4+ to P3-.
Ion
Si4+
P3-
Ionic
radius/pm
42
198
1
16. On descending Group 1 from lithium to caesium, the electronegativity of
the elements decreases. Explain clearly why the electronegativity of
elements decreases as you go down the group.
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TOTAL: 25 MARKS
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