1.
Carbon and silicon belong to the same group of the periodic table.
(a)
Distinguish between the terms group and period in terms of electron arrangement.
A group is a vertical column, where elements of the same group would have the same valence
electrons. On the other hand, periods are horizontal rows that indicate the energy levels or
are known to be the shells of the electrons.
(2)
(b)
State the period numbers of both carbon and silicon.
Carbon = period 2
Silicon= period 3
(1)
(Total 3 marks)
2.
Which statements about the periodic table are correct?
I.
Elements in period 3 have similar chemical properties.
II.
Elements in group 7 show a gradual change in physical properties.
III.
The position of an element in period 3 is related to the number of electrons in the highest
occupied energy level.
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II, and III
(Total 1 mark)
3.
The periodic table shows the relationship between electron arrangement and the properties of elements
and is a valuable tool for making predictions in chemistry.
(i)
Identify the property used to arrange the elements in the periodic table.
(1)
Chemical properties
(ii)
Outline two reasons why electronegativity increases across period 3 in the periodic table and one
reason why noble gases are not assigned electronegativity values.
Electronegativity increases across period 3 as the radius across a period decreases where there is
less shielding. Another reason why electronegativity increases across a period might be
because of the greater forces of attraction between the nucleus and the shared pairs of
electrons. One reason why noble gases are not assigned electronegativity values as they
rarely form bonds with other atoms.
(3)
(Total 4 marks)
4.
An element is in group 4 and period 3 of the periodic table. How many electrons are in the highest
occupied energy level of an atom of this element?
A.
3
B.
4
C.
12
D.
14
(Total 1 mark)
5.
Which statement is correct for all elements in the same period?
A.
They have the same number of electrons in the highest occupied energy level.
B.
They have the same chemical reactivity.
C.
They have the same number of occupied energy levels.
D.
They have the same number of neutrons.
(Total 1 mark)
6.
What are the products of the reaction between chlorine and water?
A.
O2, H2 and HCl
B.
H2 and OCl2
C.
HCl and HOCl
D.
HOCl, H2 and Cl2
(Total 1 mark)
7
(2)
(ii)
State the maximum number of orbitals in the n = 2 energy level.
8
(1)
(Total 3 marks)
8.
An atom of an element contains 19 electrons. In which group of the periodic table does it occur?
A.
1
B.
2
C.
5
D.
7
(Total 1 mark)
9.
Which property generally decreases across period 3?
A.
Atomic number
B.
Electronegativity
C.
Atomic radius
D.
First ionization energy
(Total 1 mark)
10.
Which property increases down group 1?
A.
First ionization energy
B.
Melting point
C.
Reactivity
D.
Electronegativity
(Total 1 mark)
11.
(i)
Define the term first ionization energy.
The minimal amount of energy needed to remove an electron from a gaseous atom
(2)
(ii)
Explain why the first ionization energy of magnesium is higher than that of sodium.
Mg has higher ionization energy than Na as there is a greater amount of nuclear charge in Mg
where it has a great number of protons that leads to stronger forces of attraction between
the nucleus and the electron, Na hence has a greater atomic radius where there are weaker
forces of attraction between the nucleus and the electron and therefore a higher or a geater
ionization energy.
(2)
(Total 4 marks)
12.
Which change explains why the boiling points of the halogens increase as their molecular masses
increase?
A.
The intermolecular attraction due to temporarily induced dipoles increases.
B.
The gravitational attraction between molecules increases.
C.
The polarity of the bond within the molecule increases.
D.
The strength of the bond within the molecule increases.
(Total 1 mark)
13.
Which pair of elements has the greatest difference in electronegativity?
A.
Cs and F
B.
Cs and Cl
C.
Cs and Br
D.
Cs and I
(Total 1 mark)
14.
Which statements about period 3 are correct?
I.
The electronegativity of the elements increases across period 3.
II.
The atomic radii of the elements decreases across period 3.
III.
The oxides of the elements change from acidic to basic across period 3.
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
15.
Explain why the melting points of the elements decrease down group 1 and increase down group 7.
(Total 4 marks)
16.
Which property decreases down group 7 in the periodic table?
A.
Melting point
B.
Electronegativity
C.
Atomic radius
D.
Ionic radius
(Total 1 mark)
17.
Consider the bonding and structure of the period 3 elements.
(a)
Explain the increase in the melting point from sodium to aluminium.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(b)
Explain why sulfur, S8, has a higher melting point than phosphorus, P4.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(c)
Explain why silicon has the highest melting point and argon has the lowest melting point.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 6 marks)
18.
(i)
Define the term first ionization energy of an atom.
(2)
(ii)
Explain the general increasing trend in the first ionization energies of the period 3 elements, Na to
Ar.
(2)
(iii)
Explain why sodium conducts electricity but phosphorus does not.
Sodium is metal while phosphorus is a nonmetal, metals are known to be good conductors of
electricity while nonmetals are known to be poor conductors of electricity
(2)
(Total 6 marks)
19.
Which ion has the largest radius?
A.
Cl–
B.
K+
C.
Br–
D.
F–
(Total 1 mark)
20.
(i)
Outline two reasons why a sodium ion has a smaller radius than a sodium atom.
(1) the radius of the atom is larger than that of the radius of the cation as Na holds 11 electrons whole
Na+ holds 10.
(2)
(ii)
Explain why the ionic radius of P3– is greater than the ionic radius of Si4+.
Comparing P3- and Si+4, P3- holds 18 electrons in 3 shells whereas Si+4 holds 10 electrons in 2
shells. This means that there is greater shielding in P3- and hence weaker forces of
attraction between the electron and the nucleus.
(2)
(Total 4 marks)
21.
(i)
Explain why the first ionization energy of aluminum is lower than the first ionization energy of
magnesium.
Al has lower ionization energy as it is known to be a discontinuity as the electron configuration in Mg is
shown to be: (1s2 2s2 2p6 3s2) whereas aluminum electron configuration is (1s2 2s2 2p6 3s2
3p1) this means that the electron is removed from a higher energy level in the aluminum as
it is removed from the 3p with greater shielding and weaker forces of attraction between the
nucleus and the electron
(2)
(ii)
Explain why the first ionization energy of sulfur is lower than the first ionization energy of
phosphorus.
Sulfur is shown to be lower in ionization energy as it is known to be a discontinuity, sulfurs
electron configuration is hence known to be (1s2 2s2 2p6 3s2 3p4) whereas phosphorus has
an electron configuration of (1s2 2s2 2p6 3s2 3p3) this means that sulfur has 2 pairs of
electrons in the same p orbital resulting in e-e repulsion leading to a lower ionization
energy.
(2)
(Total 4 marks)
22.
Which properties of the alkali metals decrease going down group 1?
A.
First ionization energy and reactivity
B.
Melting point and atomic radius
C.
Reactivity and electronegativity
D.
First ionization energy and melting point
(Total 1 mark)
23.
Which statements about the periodic table are correct?
I.
The elements Mg, Ca and Sr have similar chemical properties.
II.
Elements in the same period have the same number of main energy levels.
III.
The oxides of Na, Mg and P are basic.
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
24.
The x-axis of the graph below represents the atomic number of the elements in period 3.
Which variable could represent the y-axis?
A.
Melting point
B.
Electronegativity
C.
Ionic radius
D.
Atomic radius
(Total 1 mark)
25.
Which is the best definition of electronegativity?
A.
Electronegativity is the energy required for a gaseous atom to gain an electron.
B.
Electronegativity is the attraction of an atom for a bonding pair of electrons.
C.
Electronegativity is the attraction between the nucleus and the valence electrons of an atom.
D.
Electronegativity is the ability of an atom to attract electrons from another atom.
(Total 1 mark)
26.
The graph of the first ionization energy plotted against atomic number for the first twenty elements
shows periodicity.
(i)
Define the term first ionization energy and state what is meant by the term periodicity.
First ionization energy is the minimal amount of energy required to remove an electron from a
gaseous atom. Periodicity is the arrangement of patterns in chemical and physical properties
(2)
(ii)
State the electron arrangement of argon and explain why the noble gases, helium, neon and argon
show the highest first ionization energies for their respective periods.
(3)
(iii)
A graph of atomic radius plotted against atomic number shows that the atomic radius decreases
across a period. Explain why chlorine has a smaller atomic radius than sodium.
(1)
(iv)
Explain why a sulfide ion, S2–, is larger than a chloride ion, Cl–.
(1)
(v)
Explain why the melting points of the Group 1 metals (Li → Cs) decrease down the group
whereas the melting points of the Group 7 elements (F → I) increase down the group.
(3)
(Total 10 marks)
27.
Which statement describes the trends of electronegativity values in the periodic table?
A.
Values increase from left to right across a period and increase down a group.
B.
Values increase from left to right across a period and decrease down a group.
C.
Values decrease from left to right across a period and increase down a group.
D.
Values decrease from left to right across a period and decrease down a group.
(Total 1 mark)
28.
Which equation best represents the first ionization energy of magnesium?
A.
Mg(s) → Mg+(s) + e–
B.
Mg(g) → Mg2+(g) + 2e–
C.
Mg(g) → Mg+(g) + e–
D.
Mg(s) → Mg+(g) + e–
(Total 1 mark)
29.
Which species has the largest radius?
A.
Cl–
B.
K
C.
Na+
D.
K+
(Total 1 mark)
30.
Which series is arranged in order of increasing radius?
A.
Ca2+ < Cl– < K+
B.
K+ < Ca2+ < Cl–
C.
Ca2+ < K+ < Cl–
D.
Cl– < K+ < Ca2+
(Total 1 mark)
31.
Samples of sodium oxide and sulfur trioxide are added to separate beakers of water.
equation for each reaction and identify each oxide as acidic, basic or neutral.
Deduce the
1) Na2O + H2O = NaOH basic
2) SO3 +H2O= H2SO4 acidic
(Total 3 marks)
32.
Which statement about the elements in group 7 is correct?
A.
Br2 will oxidize Cl–.
B.
F2 has the least tendency to be reduced.
C.
Cl2 will oxidize I–.
D.
I2 is a stronger oxidizing agent than F2.
(Total 1 mark)
................................................................................................................................................
(Total 3 marks)
33.
State the equations for the reactions of sodium oxide, Na2O, and phosphorus(V) oxide, P4O10, with
water.
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
(Total 2 marks)
34.
(a)
State a balanced equation for the reaction of sodium with water. Include state symbols.
(2)
(b)
With reference to electronic arrangements, suggest why the reaction between rubidium and water
is more vigorous than that between sodium and water.
(2)
(Total 4 marks)
35.
Describe and explain what you will see if chlorine gas is bubbled through a solution of
(i)
potassium iodide.
(2)
(ii)
potassium fluoride.
(1)
(Total 3 marks)
36.
Which oxides produce an acidic solution when added to water?
I.
P4O10
II.
MgO
III.
SO3
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
37.
Sodium oxide, Na2O, is a white solid with a high melting point.
(a)
Explain why solid sodium oxide is a non-conductor of electricity.
......................................................................................................................................
......................................................................................................................................
(1)
(b)
Molten sodium oxide is a good conductor of electricity. State the half-equation for the reaction
occurring at the positive electrode during the electrolysis of molten sodium oxide.
......................................................................................................................................
(1)
(c)
(i)
State the acid-base nature of sodium oxide.
...........................................................................................................................
(1)
(ii)
State the equation for the reaction of sodium oxide with water.
...........................................................................................................................
(1)
(Total 4 marks)
38.
Some of the most important processes in chemistry involve acid-base reactions.
(a)
Describe the acid-base character of the oxides of each of the period 3 elements, Na to Cl.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(b)
State one example of an acidic gas, produced by an industrial process or the internal combustion
engine, which can cause large-scale pollution to lakes and forests.
......................................................................................................................................
(1)
(c)
Suggest one method, other than measuring pH, which could be used to distinguish between
solutions of a strong acid and a weak acid of the same molar concentration. State the expected
results.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 6 marks)
39.
What happens when sodium is added to water?
I.
A gas is evolved
II.
The temperature of the water increases
III.
A clear, colourless solution is formed
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
40.
Describe the acid-base character of the oxides of the period 3 elements Na to Ar. For sodium oxide and
sulfur trioxide, write balanced equations to illustrate their acid-base character.
(Total 3 marks)
Answers
1.
(a)
Group: number of outershell/valence electrons;
(b)
C: 2 and Si: 3;
Period: number of occupied (electron) shells;
2
1
[3]
2.
C
[1]
3.
(i)
atomic number / Z;
(ii)
Across period 3: increasing number of protons / atomic number / Z / nuclear charge; (atomic)
radius/size decreases / same shell/energy level / similar shielding/screening (from inner
electrons); No mark for shielding/screening or shielding/screening increases.
Accept nuclear charge / number of protons.
1
Noble gases: do not form bonds (easily) / have a full/stable octet/shell/energy level / cannot
attract more electrons; Do not accept “inert” or “unreactive” without reference to limited
ability/ inability to form bonds or attract electrons.
3
[4]
4.
B
[1]
5.
C
[1]
6.
C
[1]
7.
(i)
Group: number of valence/outer energy level electrons same;
Period: electrons are in same valence/outer energy level;
containing electrons occupied.
Accept number of energy levels
(ii)
Accept shell for energy level.
2
4;
1
Allow the mark if the correct individual orbitals (e.g. 2s etc.) are listed.
[3]
8.
A
[1]
9.
C
[1]
10.
C
[1]
11.
(i)
the amount of energy required to remove one (mole of) electron(s);
atom(s) in the gaseous state;
from (one mole of) an
2
(ii)
greater positive charge on nucleus / greater number of protons / greater core charge;
attraction by Mg nucleus for electrons (in the same shell) / smaller atomic radius;2
greater
[4]
12.
A
[1]
13.
A
[1]
14.
A
[1]
15.
Down group 1: metallic bonding gets weaker; radii/atoms get bigger / delocalized electrons
shielded/screened from nucleus by filled shells;
Down group 7: increased Mr of halogen molecules / OWTTE;
Waals/London/dispersion forces increase;
intermolecular/van der
4
[4]
16.
B
[1]
17.
(a)
as (cat)ion becomes more positive / Na+, Mg2+, Al3+ / size/radius decreases / charge density
increases; Do not allow increasing number of protons or increasing nuclear charge.
attraction for mobile/valence/delocalized/sea of electrons increases;
electrons”.
(b)
larger molecule / higher Mr/ M / greater number of electrons;
“larger/higher/greater mass”.
Do not accept “cloud of
2
Do not accept
greater van der Waals’/dispersion/London forces;
(c)
2
Si: giant/network/macromolecular/3-D covalent bonding; No mark for strong bonding without
reference to covalent and network. No mark for molecular.
Ar: (simple) atomic / (only weak) van der Waals’/dispersion/London forces;
(simple) molecular.
No mark for
2
[6]
18.
(i)
energy/enthalpy change/required/needed to remove/knock out an electron (to form +1 /unipositive/ M+1 ion); in the gaseous state; Award [1] for M(g) → M+(g) + e–. Award [2] for
M(g) → M+(g) + e– with reference to energy/enthalpy change.
2
(ii)
increasing number of protons/atomic number/Z/nuclear charge; atomic radii/size decreases /
same shell/energy level / similar shielding/ screening (from inner electrons); No mark for
shielding/screening or shielding/screening increases.
2
(iii)
Na: delocalized electrons / mobile sea of electrons / sea of electrons free to move;
for just “mobile electrons”.
P: atoms covalently bonded / no free/mobile/delocalized electrons;
No mark
2
[6]
19.
C
[1]
20.
(i)
Na: 11 p, 11/ 2.8.1 e– and Na+: 11 p, 10 / 2.8 e– / Na+ has 2 shells/ energy levels, Na has 3 /
OWTTE; Na+: has greater net positive charge/same number of protons pulling smaller number
of electrons;
2
(ii)
Si4+: 10 e– in 2 (filled) energy levels / electron arrangement 2.8 / OWTTE;
(filled) energy levels / electron arrangement 2.8.8, thus larger / OWTTE;
P3–: 18 e– in 3
OR
Si4+: has 2 energy levels whereas P3– has 3 / P3– has one more (filled) energy level;
whereas P3– has 18 e– / Si4+ has fewer electrons / P3+ has more electrons;
2
Si4+: 10 e–
[4]
21.
(i)
outer electron in Al is in 3p/p orbital/sub-shell/sub-level; higher orbital/sub-shell / e– further
from nucleus / shielded by 3s electrons;
2
(ii)
in S, electron paired in 3p/p orbital/sub-shell/sub-level;
repulsion between paired electrons (and therefore easier to remove);
2
[4]
22.
D
[1]
23.
A
[1]
24.
A
[1]
25.
B
[1]
26.
(i)
first ionization energy: M(g) → M+ (g) +e–/e / the (minimum) energy (in kJ mol–1) to remove
one electron from a gaseous atom / the energy required to remove one mole of electrons from
one mole of gaseous atoms; periodicity: repeating pattern of (physical and chemical) properties;
2
(ii)
2.8.8/sp version;
Accept any two of the following: the outer energy level/shell is full;
the nucleus; great(est) attraction for electrons;
the increased charge on
3 max
(iii)
17 p in Cl nucleus attract the outer level more than 11 p in Na nucleus / greater nuclear charge
attracts outer level more; Allow converse for Na. Do not accept larger nucleus.1
(iv)
S2– has one proton less / smaller nuclear charge so outer level held less strongly /
OWTTE; Allow converse for chloride. Do not accept larger nucleus.
1
(v)
the radii of the metal atoms increase (from Li → Cs) (so the forces of attraction are less between
them) / OWTTE; the forces of attraction between halogen molecules are van der Waals; forces
increase with increasing mass/number of electrons;
3
[10]
27.
B
[1]
28.
C
[1]
29.
B
[1]
30.
C
[1]
31.
Na2O(s) + H2O(l) → 2NaOH(aq);
basic and SO3: acidic;
SO3(l) + H2O(l) → H2SO4(aq); Ignore state symbols.
3
Na2O:
[3]
32.
C
[1]
33.
Na2O + H2O → 2Na+ + 2OH– / Na2O + H2O → 2NaOH;
symbols.
P4O10 + 6H2O → 4H3PO4;2
Ignore state
[2]
34.
(a)
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) / Na(s) + H2O(l) → NaOH(aq) + H2(g)
Award [1]
for correct balanced equation. Award [1] for correct state symbols for sodium, water, sodium
hydroxide and hydrogen. Second mark is not dependent on equation being correctly balanced.
2
(b)
(Rb more reactive because) electron lost further from nucleus so less tightly held; Rb electron
is in 5th energy level and (Na less reactive) as electron lost in 3rd energy level /
OWTTE; Allow [1 max] for electron arrangements of Na (e.g. 2,8,1) and Rb if second mark is
not scored.
2
[4]
35.
(i)
solution becomes yellow/orange/brown/darker; chlorine is more reactive than iodine (and
displaces it from solution) / OWTTE; Allow correct equation (2KI + Cl2 → KCl + I2) for
second mark or stating that iodine/I2 is formed.
2
(ii)
no colour change/nothing happens as fluorine is more reactive
than chlorine / OWTTE; 1
[3]
36.
B
[1]
37.
(a)
in the solid state ions are in fixed positions/there are no moveable ions / OWTTE; Do not
accept answer that refers to atoms or molecules.
1
(b)
2O2– → O2 + 4e– / O2– → O2 + 2e–;
(c)
(i)
basic;
(ii)
Na2O + H2O → 2NaOH / Na2O + H2O → 2Na+ + 2OH–;
Accept e instead of e–.
Allow alkaline
1
1
Do not accept 1
[4]
38.
(a)
Na, Mg: basic;
Al: amphoteric;
Do not accept amphiprotic.
Si to Cl: acidic; Award [1] for stating oxides become more basic towards left/Na and
acidic towards right/Cl. Do not penalize incorrect formulas of oxides.
3
more
(b)
NO2/nitrogen dioxide / N2O4/dinitrogen tetroxide / SO2/sulfur dioxide /
trioxide; Do not accept NO/NOx/CO2/CO.
SO3/sulfur
1
(c)
measure electrical conductivity; strong acids are good conductors/better conductors than weak
acids / weak acids are poor conductors;
OR
react with magnesium or a named active metal/metal carbonate/hydrogen
carbonate/bicarbonate; Do not accept Na/K
strong acids react faster/more gas bubbles (per unit time)/more heat produced / weak acids react
slower/less gas bubbles (per unit time)/less heat produced; Do not accept answers based on
titration curves as they are based on pH. Accept Neutralization: weak acid would produce less
energy/less temperature increase compared to a strong acid.
2 max
[6]
39.
D
[1]
40.
Oxides of: Na and Mg are basic;
Al is amphoteric; Si to Cl are acidic;
Ar has no oxide;
All four correct award [2], two or three correct award [1].
Na2O + H2O → 2NaOH and SO3 + H2O → H2SO4;
3
Must be balanced for mark. Award marks for alternative correct
equations such as SO3 with NaOH.
[3]