10.3. Chemistry
of Scandium Sc, Z=21,
1s22s22p63s23p63d14s2
data comparison of scandium
with the other members of the 3d–block and transition metals
Z
and symbol |
21
Sc |
22
Ti |
23
V |
24
Cr |
25
Mn |
26
Fe |
27
Co |
28
Ni |
29
Cu |
30
Zn |
property\name |
scandium |
titanium |
vanadium |
chromium |
manganese |
iron |
cobalt |
nickel |
copper |
zinc |
melting
point/oC |
1541 |
1668 |
1910 |
1857 |
1246 |
1538 |
1495 |
1455 |
1083 |
420 |
density/gcm–3 |
2.99 |
4.54 |
6.11 |
7.19 |
7.33 |
7.87 |
8.90 |
8.90 |
8.92 |
7.13 |
atomic
radius/pm |
161 |
145 |
132 |
125 |
124 |
124 |
125 |
125 |
128 |
133 |
M2+
ionic radius/pm |
na |
90 |
88 |
84 |
80 |
76 |
74 |
72 |
69 |
74 |
M3+
ionic radius/pm |
81 |
76 |
74 |
69 |
66 |
64 |
63 |
62 |
na |
na |
common oxidation
states |
+3
only |
+2,3,4 |
+2,3,4,5 |
+2,3,6 |
+2,3,4,6,7 |
+2,3,6 |
+2,3 |
+2,+3 |
+1,2 |
+2
only |
outer electron config.[Ar]... |
3d14s2 |
3d24s2 |
3d34s2 |
3d54s1 |
3d54s2 |
3d64s2 |
3d74s2 |
3d84s2 |
3d104s1 |
3d104s2 |
Elect.
pot. M(s)/M2+(aq) |
na |
–1.63V |
–1.18V |
–0.90V |
–1.18V |
–0.44V |
–0.28V |
–0.26V |
+0.34V |
–0.76V |
Elect.
pot. M(s)/M3+(aq) |
–2.03V |
–1.21V |
–0.85V |
–0.74V |
–0.28V |
–0.04V |
+0.40 |
na |
na |
na |
Elect.
pot. M2+(aq)/M3+(aq) |
na |
–0.37V |
–0.26V |
–0.42V |
+1.52V |
+0.77V |
+1.87V |
na |
na |
na |
Elect.
pot. = standard electrode potential data for scandium
(EØ at 298K/25oC, 101kPa/1 atm.)
na = data not applicable to scandium
Extended data table for SCANDIUM
property of scandium/unit |
value for Sc |
melting
point/oC |
1541 |
boiling
point/oC |
2836 |
density/gcm–3 |
2.99 |
1st
Ionisation Energy/kJmol–1 |
631 |
2nd
IE/kJmol–1 |
1235 |
3rd
IE/kJmol–1 |
2389 |
4th
IE/kJmol–1 |
7089 |
5th
IE/kJmol–1 |
8844 |
Sc atomic
radius/pm |
161 |
Sc3+
ionic radius/pm |
81 |
Relative polarising power Sc3+ ion |
3.7 |
oxidation
state of Sc |
+3
only |
simple electron
configuration of Zn |
2,8,9,2 |
outer electrons of Sc |
[Ar]3d14s2 |
Electrode potential Sc(s)/Sc3+(aq) |
–2.03V |
Electronegativity of Sc |
1.36 |
-
Uses of SCANDIUM
-
Scandium is a silvery–white metal
and not a particularly important element but does have some uses.
-
Scandium oxide, Sc2O3,
is used in electronic components.
-
Scandium iodide, ScI3,
is used in high intensity light–bulbs.
-
Scandium carbide, ScC, is a
hardening agent for titanium carbide, making it the second hardest
substance known.
The Chemistry
of
SCANDIUM
Pd |
s block |
d blocks (3d
block
scandium)
and
f
blocks of
metallic elements |
p block elements |
Gp1 |
Gp2 |
Gp3/13 |
Gp4/14 |
1 |
1H
|
2 |
3Li |
4Be |
Part of the modern Periodic Table of Elements:
ZSymbol, z = atomic or proton
number
Sc to Zn are now
considered the head-top elements of groups 3 to 12
3d
block of metallic elements: Scandium to Zinc
focus on scandium |
5B |
6C |
3 |
11Na |
12Mg |
13Al |
14Si |
4 |
19K |
20Ca |
21Sc
[Ar]3d14s2
scandium |
22Ti
[Ar]3d24s2
titanium |
23V
[Ar] 3d34s2
vanadium |
24Cr
[Ar] 3d54s1
chromium |
25Mn
[Ar] 3d54s2
manganese |
26Fe
[Ar] 3d64s2
iron |
27Co
[Ar] 3d74s2
cobalt |
28Ni
[Ar] 3d84s2
nickel |
29Cu
[Ar] 3d104s1
copper |
30Zn
[Ar] 3d104s2
zinc |
31Ga |
32Ge |
5 |
37Rb |
38Sr |
39Y |
40Zr |
41Nb |
42Mo |
43Tc |
44Ru |
45Rh |
46Pd |
47Ag |
48Cd |
49In |
50Sn |
6 |
55Cs |
56Ba |
57,58-71 |
72Hf |
73Ta |
74W |
75Re |
76Os |
77Ir |
78Pt |
79Au |
80Hg |
81Tl |
82Pb |
7 |
87Fr |
88Ra |
89,90-103 |
104Rf |
105Db |
106Sg |
107Bh |
108Hs |
109Mt |
110Ds |
111Rg |
112Cn |
113Nh |
114Fl |
Summary of
oxidation
states of the 3d block metals (least important) Ti to Cu are true
transition metals |
Sc |
Ti |
V |
Cr |
Mn |
Fe |
Co |
Ni |
Cu |
Zn |
|
|
|
|
|
|
|
|
+1 |
|
|
(+2) |
(+2) |
(+2) |
+2 |
+2 |
+2 |
+2 |
+2 |
+2 |
+3 (3d0) |
+3 |
+3 |
+3 |
(+3) |
+3 |
+3 |
(+3) |
(+3) |
|
|
+4 |
+4 |
|
+4 |
|
|
(+4) |
|
|
|
|
+5 |
|
|
|
|
|
|
|
|
|
|
+6 |
(+6) |
(+6) |
|
|
|
|
|
|
|
|
+7 |
|
|
|
|
|
3d14s2 |
3d24s2 |
3d34s2 |
3d54s1 |
3d54s2 |
3d64s2 |
3d74s2 |
3d84s2 |
3d104s1 |
3d104s2 |
The outer electron configurations beyond [Ar]
and the
(ground state of the simple
atom)
Note that when 3d block
elements form ions,
the 4s electrons are 'lost' first. |
The oxidation state and electron
configuration of
scandium
in the context of the 3d block of elements
-
The
electrode potential chart highlights the value for the one positive
oxidation state of scandium.
-
Scandium is quite an electropositive metal and will
dissolve in acids liberating hydrogen.
-
Scandium's
chemistry is entirely based on the +3 oxidation state (Sc3+), the result of losing the
outer 3d and 4s electrons.
-
So it forms a typical
series of binary compounds with non–metals e.g. Sc2O3, ScCl3 etc.
-
Scandium dissolves in
acids to form salts e.g. scandium chloride from hydrochloric acid.
-
2Sc(s) + 6HCl(aq) ===> 2ScCl3(aq)
+ 3H2(g)
-
Note that the Roman numerals
(III) are NOT needed in the name, since only one oxidation state is
possible for scandium and you would be expected to know that.
-
With oxygen scandium forms a
white basic oxide, scandium oxide Sc2O3,
-
2Sc(s) + 3O2(g)
===> Sc2O3(s)
-
which dissolves in acids to
form colourless solutions of the respective salt e.g.
-
Sc2O3(s)
+ 6HCl(aq) ===> 2ScCl3(aq) + 3H2O(l)
(scandium chloride)
-
Sc2O3(s)
+ 3H2SO4(aq) ===> Sc2(SO4)3(aq)
+ 3H2O(l)
(scandium sulfate)
-
Sc2O3(s)
+ 6HNO3(aq) ===> 2Sc(NO3)3(aq) + 3H2O(l)
(scandium nitrate)
-
The scandium(III) ion, Sc3+
ion, [Sc(H2O)6)]3+
has an empty sub–shell, 3d0, which does not allow the
electronic transitions which account for the colour in transition
metal compounds.
-
The aqueous
octahedral hexaaqua ion of scandium,
[Sc(H2O)6]3+ is therefore colourless
(shown as grey in the diagram!) and with no other oxidation state possible i.e. no ion with an
incomplete 3d sub–shell with at least one electron, although a
member of the 3d–block, scandium is NOT a true transition metal.
-
With
alkali, the aqueous scandium ion
Sc3+ forms a white gelatinous precipitate of hydrated scandium hydroxide, Sc(OH)3,
-
Sc3+(aq) +
3OH–(aq) ==> Sc(OH)3(s)
-
Formula for
the neutral hydroxide complex is
[Sc(OH)3(H2O)3]0
-
Scandium hydroxide is
a basic hydroxide and not
amphoteric i.e. it does not dissolve in excess alkali, but scandium
hydroxide readily
dissolves in acids to form salts e.g. to form scandium chloride,
scandium nitrate or scandium sulfate ...
-
Sc(OH)3(s)
+ 3HCl(aq) ===> ScCl3(aq) + 3H2O(l)
-
Sc(OH)3(s)
+ 3HNO3(aq) ===> Sc(NO3)3(aq) +
3H2O(l)
-
2Sc(OH)3(s)
+ 3H2SO4(aq) ===> Sc2(SO4)3(aq)
+ 6H2O(l)
-
The chemistry of
scandium is not very colourful or exciting, but scandium is not without
its uses!
-
The equations are
similar to those for aluminium hydroxide i.e. you can substitute Al for
Sc, but not the amphoteric character of aluminium oxide/hydroxide.
-
Summary of some
complexes–compounds & oxidation state of scandium compared to other
3d–block elements
The
vertical connection of scandium with the other d-block elements of
Group 3 (IUPAC designation)
Modern group numbers of 3-12 |
Outer electron
structure of d-block elements which includes the transition metals
Scandium is the head element of Group 3 plus Yttrium, Lanthanum and
Actinium
Their
outer electron
configurations are nd1(n+1)s2
(where n = 3 to 6)
|
[e- core] |
Gp 3 |
Group
4 |
Group
5 |
Group
6 |
Group
7 |
Group
8 |
Group
9 |
Group
10 |
Group
11 |
Group
12 |
P'd 4,
3d block [Ar] core |
21Sc
3d14s2 |
22Ti
3d24s2 |
23V
3d34s2 |
24Cr
3d54s1 |
25Mn
3d54s2 |
26Fe
3d64s2 |
27Co
3d74s2 |
28Ni
3d84s2 |
29Cu
3d104s1 |
30Zn
3d104s2 |
P'd 5, 4d block (Kr] core |
39Y
4d15s2 |
40Zr
4d25s2 |
41Nb
4d45s1 |
42Mo
4d55s1 |
43Tc
4d55s2 |
44Ru
4d75s1 |
45Rh
4d85s1 |
46Pd
4d10 |
47Ag
4d105s1 |
48Cd
4d105s2 |
P'd 6,
5d
b'k [Xe] core |
57La
5d16s2 |
72Hf
4f145d26s2 |
73Ta
4f145d36s2 |
74W
4f145d46s2 |
75Re
4f145d56s2 |
76Os
4f145d66s2 |
77Ir
4f145d76s2 |
78Pt
4f145d96s1 |
79Au
4f145d106s1 |
80Hg
4f145d106s2 |
P'd 7, 6d b'k
[Rn] core |
89Ac
6d17s2 |
104Rf
5f146d27s2 |
105Db
5f146d37s2 |
106Sg
5f146d47s2 |
107Bh
5f146d57s2 |
108Hs
5f146d67s2 |
109Mt
5f146d77s2 |
110Ds
5f146d87s2 |
111Rg
5f146d97s2 |
112Cn
5f146d107s2 |
-
There are two other
metals which are also considered members of Group 3, lutetium and
lawrencium.
You sometimes see them
placed where La and Ac are in the above table, but these two are
technically the end elements in the horizontal 4f and 5f blocks
series of metals.
Lutetium 71Lu:
Electron configuration [Xe]4f145d16s2.
Lawrencium 103Lw:
Electron configuration [Xe]5f147s27p1.
See the fully expanded periodic table and electron
configurations with all groups and series shown
!!!
keywords and phrases: Why are scandium
compounds ions complexes colourless? equations for scandium reacting with acids,
equations for scandium oxide reacting with strong acids, equations for scandium
hydroxide reacting with acids to give scandium(III) salts, ligand
substitution displacement balanced equations
formula complex ions complexes ligands colours oxidation states: scandium ions
Sc(0) Sc(III) Sc(+3) Sc3+ [Sc(H2O)]3+ 2Sc + 6 HCl ==> 2 ScCl3 + 3H2 2Sc + 3O2
==> Sc2O3 + 6 HCl ==> 2ScCl3 + 3H2O Sc2O3 + 3 H2SO4 ==> Sc2(SO4)3 +
3H2O Sc2O3 + 6 HNO3 ==> 2Sc(NO3)3 + 3H2O Sc3+ + 3OH– ==> Sc(OH)3 + 3HCl
==> ScCl3 + 3H2O Sc(OH)3 + 3HNO3 ==> Sc(NO3)3 + 3H2O 2Sc(OH)3 + 3H2SO4 ==>
Sc2(SO4)3 + 6H2O [Sc(OH)3(H2O)3] oxidation states of scandium, why there are no redox reactions
of scandium involving change of oxidation state for more than one ion of
scandium, ligand substitution displacement reactions of scandium, balanced
equations of scandium chemistry, formula of scandium complex ions, shapes
colours of scandium complexes with water and hydroxide ion the position of
scandium in the periodic table its reactivity with acids, quite a negative
electrode potential half-cell potential
WHAT NEXT?
GCSE Level Notes on Transition
Metals (for the basics)
The chemistry of
Scandium
* Titanium * Vanadium
* Chromium
* Manganese
The chemistry of
Iron * Cobalt
* Nickel
* Copper *
Zinc
*
Silver & Platinum
Introduction 3d–block Transition Metals * Appendix
1.
Hydrated salts, acidity of
hexa–aqua ions * Appendix 2. Complexes
& ligands * Appendix 3. Complexes and isomerism * Appendix 4.
Electron configuration & colour theory * Appendix 5. Redox
equations, feasibility, Eø * Appendix 6.
Catalysis * Appendix 7.
Redox
equations
* Appendix 8. Stability Constants and entropy
changes *
Appendix 9. Colorimetric analysis
and complex ion formula * Appendix 10 3d block
– extended data
* Appendix 11 Some 3d–block compounds, complexes, oxidation states
& electrode potentials * Appendix 12
Hydroxide complex precipitate 'pictures',
formulae and equations
Some
pages have a matching sub-index
Advanced
Level Inorganic Chemistry Periodic Table Index:
Part 1
Periodic Table history
Part 2
Electron configurations, spectroscopy,
hydrogen spectrum,
ionisation energies *
Part 3
Period 1 survey H to He *
Part 4
Period 2 survey Li to Ne * Part
5 Period 3 survey Na to Ar *
Part 6
Period 4 survey K to Kr AND important
trends down a group *
Part 7
s–block Groups 1/2 Alkali Metals/Alkaline Earth Metals *
Part 8
p–block Groups 3/13 to 0/18 *
Part 9
Group 7/17 The Halogens *
Part 10
3d block elements & Transition Metal Series
*
Part 11
Group & Series data & periodicity plots
All
11 Parts have
their own sub-indexes near the top of the pages
Group numbering and the modern periodic
table
The original group numbers of
the periodic table ran from group 1 alkali metals to group 0
noble gases. To account for the d block elements and their
'vertical' similarities, in the modern periodic table, groups 3
to group 0 are numbered 13 to 18. So, the p block elements are
referred to as groups 13 to group 18 at a higher academic level,
though the group 3 to 0 notation is still
used, but usually at a lower academic level. The 3d block
elements (Sc to Zn) are now considered the head (top) elements
of groups 3 to 12.
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worksheets etc. Copying of website material is NOT permitted. Doc
Brown's Chemistry theoretical-physical chemistry revision notes for
pre-university level students on d-block elements including the
physical and chemical properties reactions equations and trends
explained for the 3d-block of transition metals series
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