Download General Properties of Transition Metals

TRANSITION ELEMENTS:
• Lie within the d-block elements
• Titanium  Copper
• Metals
Physical properties
 Conductors of heat & electricity
 Shiny, strong & hard
 High melting & boiling points
Zinc is a d-block
element but NOT
transition
element…you will
see why later!
GENERAL PROPERTIES
• The general properties of transition metals are:
Chemical properties
– they form complexes
– they form coloured ions
– they form variable oxidation states
– they have catalytic activity
ELECTRONIC STRUCTURE
• All characteristic properties are a result of their
electronic structure
• The transition metals have a partially filled 3d
energy sub level in their atoms or ions
• In general there are two outer 4s electrons, and
electrons are added to the inner 3d sub level
CHROMIUM & COPPER
• In chromium the 4s13d5 structure is adopted because the
repulsion between two paired electrons in the 4s orbital is
more than the energy difference between the 4s and 3d
subshells
• It is therefore more stable to have unpaired electrons in
the higher energy 3d orbital than paired electrons in the
lower energy 4s orbital.
• For copper it is more stable to have fully paired 3d shell.
1 electron drops from the 4s to achieve this and give
4s13d10
FORMING IONS
• In all ions of d-block elements, the 3d subshell is lower in
energy than the 4s subshell
• So the 4s electrons are always removed first
• 3d electrons are only removed after all 4s electrons have
been removed
• E.g. Fe = [Ar]3d64s2

Fe2+ = [Ar]3d6
• E.g. Fe2+ = [Ar]3d6

Fe3+ = [Ar]3d5
CONFIGURATION OF D-BLOCK IONS
Give the electronic structure of the following ions:
• Sc3+
1s2 2s2 2p6 3s2 3p6
• Fe2+
1s2 2s2 2p6 3s2 3p6 3d6
• Co3+
1s2 2s2 2p6 3s2 3p6 3d6
• Cu+
1s2 2s2 2p6 3s2 3p6 3d10
DEFINING A TRANSITION ELEMENT
• A transition element is one that forms at least one
stable ion with a part full d-shell of electrons
• Zinc only forms Zn2+ (3d10)
• It is a d-block elements and not a transition element
Oxidation Numbers shown by first row d-block elements
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
+I
+I
+I
+I
+I
+I
+I
+I
+I
+II
+II
+II
+II
+II
+II
+II
+II
+II
+III
+III
+III
+III
+III
+III
+III
+III
+III
+IV
+IV
+IV
+IV
+IV
+IV
+IV
+V
+V
+V
+V
+V
+VI
+VI
+VI
+VII
Most common oxidation states highlighted (not all stable)
Complete the sheet to assess your progress
Zn
+II
ANSWERS:
1 a) [Ar]3d34s2
1 b) [Ar]3d74s2
1 c) [Ar]3d104s1
1 d) [Ar]3d84s2
2) Physical Properties – high density, high melting points,
high boiling points, hard, shiny
Chemical properties – form complex ions, form coloured
ions, act as catalysts, exist in variable oxidation states
ANSWERS:
3) A metal that can form one or more stable ions with a
partially filled d-subshell
4) Electrons fill up the lowest energy subshells first.
Electrons fill orbitals singly before sharing
5) Zinc has the configuration [Ar]3d104s2. It can only form
Zn2+ ions ([Ar]3d10). This ion has a full 3d-subshell. Zinc
cannot form a stable ion with a partially filled 3d-subshell
so it is not a transition metal.
ANSWERS:
6) Chromium prefers to have one electron in each orbital
of the 3d subshell and just one in the 4s as this gives it
more stability
7) Copper prefers to have a full 3d subshell and just one
electron in the 4s because this gives it more stability.
8 a) [Ar]3d2
8 b) [Ar]3d7
8 c) [Ar]3d9
8 d) [Ar]3d8
• Neutral molecule or ion having a lone electron
pair that can be used to form a bond to a metal
ion.
 Monodentate ligand – one bond to a metal ion
 Bidentate ligand (chelate) – two bonds to a
metal ion
 Polydentate ligand – more than two bonds to a
metal ion
• Transition metals can form complexes because
their ions have a high charge density:
o they have quite a large nuclear charge but are
relatively small;
o the 3d electrons are not so effective (as 2s or 2p
electrons) at shielding the effect of the ionic charge
which really comes from the nucleus.
• This allows the transition metal ions to have a
great polarising power and they can attract lone
pairs from other atoms to form complexes.
• Ions formed by a metal ion to which a number
of ligands (molecules and/or negative ions)
are bonded using a dative bond
• Example:
[Fe(H2O)6]3+
• Coordination number is the number of ligands
that surround the metal ion
[Fe(CN)6]3-
[CuCl4]2-
[Cu(NH3)4]2+
[Ag(NH3)2]+
Charge on the ion is the sum of all charges.
Work out the charge of each metal ion in
the complexes above.
H2O
OHNH3
ClBrCN-
-
-
ligand
aqua
hydroxo
ammine
chloro
bromo
cyano
number
1 - mono
2 - di
3 - tri
4 - tetra
5 - pent
6 – hex
You name the ligand and its number first before naming the
metal. You use the name of the metal if the ion is positive but
use –ate ending if negative e.g. ferrate, cuprate, vanadate.
Depends on coordination number
• If 6
• If 4
• If 2
then shape = octahedral
then shape = tetrahedral
(or square planar = less common)
then shape = linear
• nuclear charge
• oxidation state of ion (i.e. number of
electrons)
• ligand
• coordination number
• shape of the complex