1.	D
[1]

2.	D
[1]

3.	B
[1]

4.	(i)	complex (ion) / the charge is delocalized over all that is contained in
the brackets;	1
 
(ii)	colour is due to energy being absorbed when electrons are promoted
within the split d orbitals;
the colour observed is the complementary colour to the energy
absorbed / OWTTE;
Accept either answer for first mark.
	changing the ligand / coordination number / geometry changes
the amount the d orbitals are split/energy difference between the
d orbitals / OWTTE;	2 max
[3]

5.	D
[1]

6.	Sc has no d electrons as an ion / Cu has d electrons;
Cu compounds are coloured / Sc compounds are colourless;
Cu has more than one oxidation state / Sc has only one oxidation state;
Cu compounds can act as catalysts / Sc cannot act as catalysts;	3 max
[3]

7.	A
[1]

8.	(i)	Lewis acid-base (reaction);
H_2O: e^– pair donor, Fe^3+: e^– pair acceptor / H_2O donates an electron pair to Fe^3+;	2
 
(ii)	d sub-levels are split into two sets of orbitals (of different energies);
electron transitions between (d) orbitals of different energies /
d-d transition(s);
transmitted (visible) light is complementary colour;	3
[5]

9.	D
[1]

10.	d orbitals are split (into two sets of different energies);
frequencies of (visible) light absorbed by electrons moving from lower to higher
d levels;
colour due to remaining frequencies/complementary colour transmitted;
Cu^2+ has unpaired electrons/partially filled d sub-level;
Zn^2+ has filled d sub-shell;
electronic transitions/d-d transitions possible for Cu^2+ / no electronic/d-d transitions
possible for Zn^2+;
Allow wavelength as well as frequency.	4 max
[4]

11.	NH_3: Lewis base / Cu^2+: Lewis acid;
each NH_3 /ligand donates an electron pair (to Cu^2+);
NH_3 replace H_2O ligands around Cu^2+ ion/around central ion;
forming coordinate (covalent)/dative covalent bond;	3 max
[3]

12.	C
[1]

13.	(i)	+2;	1
 
(ii)	+3;	1
 
(iii)	+2;
Only penalize once if roman numerals are used or if written as 2+ or 3+.	1
[3]

14.	(i)	(Cu) 1s^22s^22p^63s^23p^64s^13d^10 / 1s^22s^22p^63s^23p^63d^104s^1;
Do not accept [Ar]4s^13d^10.
	(Cu^+) 1s^22s^22p^63s^23p^63d^10;
Do not accept [Ar]3d^10.	2
 
(ii)	Cu^2+ has an incomplete d sub-level and Sc^3+ has no d electrons;
the d sub-level is split so the d electrons (in copper) can be excited by
visible light / OWTTE;	2
[4]

15.	(a)	(i)	dumbbell-shaped representation along the z-axis:

Sign of wave function not required.	1
 
(ii)	1s^22s^22p^63s^23p^63d^5 / 1s^22s^22p^63s^23p^64s^03d^5 / [Ar]4s^03d^5 / [Ar]3d^5;
Do not allow 2, 8, 13.	1
 
(iii)	Lewis base / (species/ion/molecule) with lone pair and dative
covalent/coordinate bond (to metal) / bonds with metal (ion)/
complex ion;	1
 
(iv)	has partially filled d subshell/sublevel/orbitals;
d orbitals are split (into two sets of different energies)
colour due to electron transition between (split) d orbitals;
frequencies of visible light absorbed by electrons moving from lower
to higher d levels, colour due to remaining frequencies;
Allow wavelength as well as frequency.	3 max

(v)

Accept half-arrows or full arrows.
Do not penalize if additional sublevels are shown, if sublevels are
not labelled or if no boxes are drawn (providing system of
arrows correct).
Do not award mark if sublevels are incorrectly labelled.
Orbital diagram may also be represented with sublevels shown
at different relative energy positions.	1
[7]

16.	C
[1]

17.	[Fe(CN)_6]^4– = +2;
[FeCl_4]^– = +3;
Award [1 max] if 2+ and 3+, 2 and 3 or II and III stated.	2
[2]

18.	A
[1]

19.	C
[1]

20.	(i)	an ion or molecule, with a lone pair of electrons that coordinates to a metal
atom or to a metal ion to form a complex / (OWTTE) and cyanide/CN^−;	1
 
(ii)	Fe^3+ = 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^5;
[Ar] | ↑ | ↑ | ↑ | ↑ | ↑ | ;
	3d^5
	5 unpaired electrons;	3

(iii)	presence of unpaired electrons;
the d orbitals are split into two energy levels;
electrons move between these energy levels;
absorb energy from light of visible wavelength / OWTTE;	3 max
Award [1] each for any three.
[7]

IB Questionbank Chemistry