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Study the structure of her::~shc.rn in tbe ~i":otcgr2ph on psqe 103.
28
(a)
\f!har is ~heoxidation stare of Ih~ cenrral iron ion?
of the nitroqen atoms around the central iron ion?
(hl
V-:h2l;5 geome,ry
(e)
Explain why the complex is ideally suited ro carry oxygen around the body
Name the (ata{ysI in each of the followinq processes:
(a) The hydrogenation of vegetable oils ::0 form margarfn"'e:
29
Tne manufacture.
(b}
of sulfuric acid in the Contact process.
(e) The removal of carbon and nitrogen monoxide from exhaust emissions.
30' (a)
Distinguish between hornoqeneous
and heterogeneous
catalysis.
Explain tNhy the transition metals make effective heterogeneous
(b)
'fc) Expiain why heterogeneous
catalysts.
csralysts ere generaiiy used in lndu5tf2i precesses.
1 For which element are the group number and the period number the same?
C B
B Be
A Li
D Mg
© Intemational Baccalaureate Organization [2004]
2 Which properties of Period 3 elements increase from sodium to argon:
I
II·
III
nuclear charge
atomic radius
electro negativity?
A I and II only
B ! and HI only
(
II
and
III
only
D 1,11 and If!
© International Baccalaureate Organization [2003]
3 Which pair of elements reacts most readily?
A Li + Br2
B Li + (12
(
K + Br2
D K + (12
© lnternational Baccaiaureate Organization [2003J
4 Which of the reactions below occur as written?
Br2 + 21- ~ 2Br- + 12
A l only
B II only
C both I and II
D neither 1 nor"
© International Baccalaureate Organization [2004J
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5 Explain the following statements,
(a) The first ionization energy of sodium is:
(i)
(ii)
less than that of magnesium.
(2)
greater than that of potassium.
(1)
(b) The electronegativity of chlorine is higher than that of sulfur,
(2)
(Total 5 marks)
© International Baccalaureate Organization [2003]
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• Examiner's hint:
6 Describe the acid-base character of the oxides of the Period 3 elements Na to Ai. For
sodium oxide and sulfur trioxide, write balanced equations to illustrate their acid-base
~~
~
© international oaccarallreate Organization [2003]
Learn balanced
eouettons for add-base reactions of
the Period 3 oxides. :\4cke sure that you
un.dE:r5~and 31itne chemical equations
presented
in this topic. You could be
2XpeC!2d IO reproduce them under
exam conditions.
7 Atomic radii and ionic radii are found in the 18 Data booklet.
Explain why:
{a} the magnesium ion is much smaller than the rnaqnesiurn atom.
(b) there is a large increase in ionic radius from silicon to phosphorus.
(c) the ionic radius of Na';- is less than that of F-.
• Examiner's hint:
(2)
In deaiing with
It~e
'crux' of tne question.
in (a), it is the
(2)
(2)
..
(Total 6 marks)
© International Baccalaureate Organization [2003}
loss of 31: enerqy leVEL In (b),
j"
is the
difference of a whole energy level and
mere snouid oe some comment en
lsoelectroruc nature of the two ions and
8 (a) Classify each of the foliowing oxides as acidic, basic or amphoteric.
(i) aluminium oxide
(ll) sodium oxide
(iii) sulfur dioxide
(b}
(1)
(1)
(1)
Write an equation for each reaction between water and
(i) sodium oxide
(ii) sulfur dioxide.
(1)
(1)
{Tota! 5 marks}
© tntemational Baccalaureate Orqanization [2005]
9 State and explain the trends in the atomic radius and the ionization energy
(a)
(b)
for the alkali metals Lito Cs.
for the Period 3 elements Na to
(4)
CL
(4)
ttotet 8 marks)
© International Baccalaureate Organization [2005J
H)· The IB Data
booklet gives the atomic and ionic radii of elements. State and explain the
difference between
(a) the atomic radius of nitrogen and OAygen
(2)
(b) the atomic radius of nitrogen and phosphorus
(1)
(e) the atomic and ionic radius of nitrogen
(2)
itotsl 5 marks)
© lnternational Baccalaureate Organization [2004f
11
Which is an essential feature of a ligand?
A a negative charge
B an odd number of electrons
( the presence of two or more atoms
o the presence of a non-bonding pair of electrons
© Intemational Baccalaureate Organization (2005)
12. By reference to the structure and bonding in the compounds NaCi and SiCi~:
(a) state and explain the dfferences in conductivity in ~E Hquid 5tatE.
(3)
(b) predict an approximate pH vaiue for a solution formed by adding each compound
separately to water.
.
(4)
(Tota! 7 markS)
© International Baccalaureate Organization (2005)
o Examiner's hint: When asked to
predict a pH value, to write 'a row vaiue'
oran acidic value' is nor sufficient.
Periodicity
_
I
13 Elements with atomic number 21 to 30 are d-block elements.
I
(a)
Identify which of these elements·are not considered to be typical transition
elements.
!
I.
I
(1)
(b) Complex ions consist of a central metal ion surrounded by ligands. Define the term
iigand.
(2)
(c)
Complete the table below to show the oxidation state of the transition
element.
(3)
lion
I Oxidation state
(d)
Cr20l-
I
I
I
[(u(14]2-
[Fe{H20)ol''''
r
I
I
Identify two transition elements used as catalysts in industrial processes, stating
~ flop
in
~!._ prr.,pee
•.•..•••......••
_ •••
(e)
I
I
each
_ •..••
'2)
t r=Q
•••
o-~....
\
Apart from the formation of complex ions and apart from their use as catalysts,
state two other properties of transition elements.
(2)
(Tota/l0 marks)
© International Baccalaureate Organization (2004)
14 (a)
(b)
State two possible oxidation states for iron and explain these in terms of electron
arrangements.
(2}
Explain why many compounds of d-block (transition) elements are coloured.
(3)
(Total 5 marks)
© international
Baccalaureate Organization
(2005)
15 The colour of transition metal complexes depends on several factors.
(a)
Use [Mn(H20)6j2+ and [Fe(Hl0)6F+ as examples to outline why the colour
depends on the identity of the transition metal itself.
(3)
(b)
Outline why the colour depends on the oxidation state of the transition meta!.
(1)
(c)
Outline why the colour depends on the identity of the ligand.
(1)
(TotalS marks)
© International Baccalaureate Organization (2003)
,-
16 Outline the reasoning for the following in terms of electronic configuration:
(a)
The first ionization energy of AI is lower than that of Mg.
(b)
V3+(aq) is coloured and can behave as a reducing agent, whereas Znh(aq)
(2)
(6)
is not coloured and does not behave as a reducing agent.
(Total 8 marks)
© International Baccalaureate Organization (2003)
11 (a)
Explain, in terms of their structure and bonding, why the element sulfur is a nonconductor of electricity and aluminium is a good conductor of electricity.
(4)
(b)
Explain, in terms of its structure and bonding, why silicon dioxide, SiOl, has a high
(e)
Silicon tetrachloride, 5i(14, reacts with water to form an acidic solution.
melting point.
(2)
(f) Explain why silicon tetrachloride
(ii)
has a low melting point.
(2)
Write an equation for the reaction of silicon tetrachloride with water.
(1)
(Total 9 marks)
© International Baccalaureate Organization (2005)
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Answers
------------------
--------~
LB
3. D
2. B
5. (a)
4.A
(i) N? has 101\-ernuclear charge f number of protons;
electrons removed are from same energy level r
shell, N? has larger radius r electron further from
the Bticleu.s;
~
(2 max)
(ii) Na electron closer to nucleus / in lower energy
level / Na has less shielding effect;
(L)
(b) chlorine has a higher effective nuclear charge; attracts
the-electron pair i electrons in bond more strongly;
(2)
(TotalS marks)
6. oxides of:
Na, Mg: basic;
Al; amphoteric,
Si to C1: acidic;
Ar: no oxide;
Na10 + H20 --;-2NaOH;
S03
+ H;O
-+
H1SO,-'
(4)
7,_ (a) loss of 2 electrons j outer electrons; 3 shells to 2; net
attractive force increases;
(2 max)
(b) p3- has one more shell than Si';-;-;some justification in
terms of electron loss! gain, net attractive forces; l2 max)
(c) same electron arrangement! both have two complete
shells; extra protons in ]\!a7 (attract the electrons more
strongly);
(2)
(Total 6 marks)
8. (a)
(i) aluminium oxide: amphoteric:
sodium oxide: basic;
(ill} sulfur dioxide: acidic;
(b) (i) NalO + H20 --;2Na~ -i- 2mr;
(ii) SOl + H20 ~-H2S03;
Accept NaOH; and H'" + HSO J 12H7
(1)
(1)
(1)
(1)
(1)
(ii)
9. (a) Li to Cs:atornic
+ SOr,
(Total S marks)
radius increases;
because more full energy keels are used or ~
/
orrrereiectrons further from nucleus! outer electrons ina higher shell: ionization energy decreases;
because the electron removed is further from the nucleus
/ increased. repulsion by inner-shell electrons;
(4)
Accept iJ!crea5ed shielding effect.
(b) Sa to Cl: atomic radius decreases;
because nuclear charge increases and electrons are added
to S2JTIC main (outer) energy level:
ionization energy increases,
because nuclear charge increases and the electron removed
is closer to the nucleus / is the same energr level;
(-10_
,,-{ccept 'core charge' for 'nuclear dtarge~
In (a) and (b) explanation. mark is dependent 011 correct
(TotalS
j)J{Jr.!;s
> 0 because 0 has greater nuclear
charge;
greater attraction for the outer electrons / OWTTE.; (:
{by atomic radius ofP > N because P has outer-electr-ons ii:c
an energy level further from the nucleus I O\VTTE;
10, (a) atomic radius ofN
-----------------------~
(c) N3- > N / ionic radius> atomic radius because N3- has
more electrons than protons; so the electrons are held
less tightly / OI"/TT£;
(2)
Award (1) for greater repulsion in N3- due to more
electrons (110 reference to protons).
(TotalS marks)
H.D
12. (a) NaCl conducts and SiC!4 does not;.
NaCl ionic and SiCl~ covalent;
(3)
ions can move in liquid (in NaCl) 1 OWTTE;
(b) NaC! pH = 7;
salt of strong acid and strong base I Na+ and Cl" not
hydrolysed;
SiCl4 pH = 0 to 3;
~ (4)
HCl is fanned! strong acid formed;
(Total 7 marks)
13.(a) scandium and zinc! Scand Zn:
(1)
Both needed for the mark.
Accept copper 1 Cu if given in addition to Sc and Zn i.e.
all three needed for the mark.
(0) species / neutral molecules; anions which contain a
non-bonding pair of electrons; able to form coordinate /
dative covalent bonds;
(2)
(c)
lIon:
......•... ·.1 Cr20t
I Oxidation state f
+6
I [CUCl4F~
I [Fe(HzO)6P"" ,
f
I
-..<
+3
f (3)
Accept 6+,2+, 3+. If given as 6,2,3 or (VI), (ti), (m), award
(2) only.
(d) Y /Y20S in the contact process;
Fe in the Haber process;
Ni in the conversion of alkenes to alkanes t
hydrogenation reactions;
(2 rnax)
Award (1) each for any two.
Accept any other suitable examples.
(e) variable oxidation states; coloured compounds;
(2)
Accept any other suitable examples.
(TOtal 10 marks)
14. (a) +2 and +31 Fe2"" and Fe3+;
both s electrons are lost giving Fel-'- and one more d
electron is also lost to form Feh;
(2)
(b) presence of unpaired electrons;
the d orbitals are split into two energy levels;
electrons move between these energy levels;
electrons can absorb energy from light of visible wavelength
Q-WTTE;
(3)
Award (1) each for any three.
(Total 5 marks)
15. (a) [lvIn(H20)6P+ is pink / colourless and [Fe(H20)sF+ is
green'! the colours they show ~re comp~mentary to the
colours they absorb;
'."-.,",
colour is ca'used by transitions between the d orbitals;
different metals cause the d orbitals to split differently
(due mainly to the different number of protons in the
nude us);
(3)
(b) the oxidation state affects the size-of the d orbital splitting
due to the different number of electrons present
(1)
(c) the more electron-dense the ligand the greater the
(1)
splitting of the d orbitals
(TotalS marks)
•••
16. (a) Mg: 352 and AI: 3s"3p! (Heed both for mark);
3p electron is higher in eIfergy than 3s (and easier to
remove);'
(2)
(b) v=. [Arj3d3 and Zn2+: [Arj3diO (need both for mark);
colour due to splitting of partially filled d orbitals (at
different energy levels);
electronic transitions between these are responsible for
colour;
V3+ has partially filled d orbitals I ZnH does not;
V3-;- not in its highest oxidation state (and can be oxidized);
Zn2+ in its highest oxidation state (and cannot be
further oxidized);
(6)
(Tot.1l8 marks)
Ii (a) sulfur is (simple) molecular;
(contains) covalent bonds / no delocalized electrons all
(outer) electrons used in bonding;
aluminium contains positive ions and delocalized
electrons;
(delocalized) electrons move (when voltage applied or
current flows);
(4)
(b) silicon dioxide is macromolecular l giant covalent;
many! strong covalent bonds must be broken,
(2)
Award max (1) if 110 mention of covalent.
Do not accept weakened instead of broken.
(c) (i) van der Waals' forces (between molecules);
Accept London or dispersion forces or temporary
dipole-dipole attractions:
(these forces are) weak / easily overcome;
(2)
(d) SiCI. + 4H20 ~ Si(OH)~ + 4HCI;
(1)
Ignore state symbols, accept as product SiO]' 2H20 or
H~SiO~
(Total 9 marks)
r