Transition Elements
Transition elements are d block elements
that have an ion with an incomplete d
subshell.
Element Electronic Configuration
Zinc and Scandium are not
transition elements!
Scandium forms only one ion, Sc3+. In forming this
ion, scandium loses the two electrons in the 4s
subshell and the one electron in the 3d subshell.
This leaves the ion with no d subshell – it therefore
isn’t a transition metal.
Zinc forms only one ion, Zn2+. In forming
this ion, zinc loses the two electrons in
the 4s subshell. This leaves the ion with a
complete d subshell – it therefore isn’t a
transition metal.
Sc
1s22s22p63s23p6 4s23d1
Ti
1s22s22p63s23p6 4s23d2
V
1s22s22p63s23p6 4s23d3
Cr
1s22s22p63s23p6 4s13d5
Mn
1s22s22p63s23p6 4s23d5
Fe
1s22s22p63s23p6 4s23d6
Co
1s22s22p63s23p6 4s23d7
Ni
1s22s22p63s23p6 4s23d8
Cu
1s22s22p63s23p6 4s13d10
Zn
1s22s22p63s23p6 4s23d10
Note that chromium and copper don’t fit the pattern.
They fill their 3d subshell before their 4s subshell.
Transition Metals have variable Oxidation States
Fe3+ + e-
Oxidation States of Manganese
+2
in Mn2+
+3
in Mn2O3
+4
in MnO2
+6
in MnO42-
+7
in MnO4-
Fe2+
Pale green  Yellow
Cr2O72- + 6H+ + 6e-
2Cr3+ + 7H2O
MnO4- + 8H+ + 5e-
Mn2+ + 4H2O
Orange  Green
Purple  Pale Pink
Precipitation reactions of Transition Metals
Metal Ion & Colour
Precipitate
Cu2+ - Blue Solution
Cu(OH)2 -Blue
Co2+ - Pink Solution
Co(OH)2 -Blue
Fe2+- Pale Green Solution
Fe(OH)2 - Green
Fe3+ - Yellow Solution
Fe(OH)3 - Brown
1.
2.
3.
4.
N2 + 3H2  2NH3
CH2= CH2 + H2 CH3CH3
3. 2SO2 + O2  2SO3
4. H2O2  H2O + ½ O2
Catalytic Activity
1. Iron in the Haber Process: combines hydrogen
and nitrogen to make ammonia
2. Nickel in the hydrogenation of C=C bonds:
manufacture of margarine from vegetable oils.
3. Vanadium(V) oxide in the Contact Process:
reaction which converts sulphur dioxide into
sulphur trioxide. Sulphur dioxide gas is passed
together with air (as a source of oxygen) over a
solid vanadium(V) oxide catalyst.
4. Manganese (IV) Oxide in the decomposition
of hydrogen peroxide