, Research Paper
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(a) High Melting Point and Boiling Point The bonding between the atoms in transition metals is very strong. The strong
attractive force between the atoms is only weakened at high temperatures, hence
the high melting points and boiling points. For example: iron melts at
1535?C and boils at 2750?C BUT a Group 1 Alkali Metals such as sodium melts at
98?C and boils at 883?C. (b) High density Another consequence of the strong bonding between the atoms in transition
metals is they are tightly held together to give a high density. For example: iron has a density
of 7.9 g/cm3 and sodium has a density of 0.97 g/cm3 (and
floats on water while fizzing! water has a density of 1.0
g/cm3). (c) Form coloured compounds and ions in solution Transition metals tend to form more coloured compounds more than other
elements either in solid form or dissolved in a solvent. The colours of some
transition metal salts in aqueous solution are shown below. 1
2
3
4
5
6
7
8
9
10
Sc – scandium salts such as the chloride, ScCl3, are co
and not typical of transition metals
Ti – titanium(III) chloride, TiCl3, is purple
V – vanadium(III) chloride, VCl3, is green
Cr – chromium(III) sulphate, Cr2(SO4)3, is
dark green
Mn – potassium manganate(VII), KMnO4, is purple
Fe – iron(III) chloride, FeCl3, is yellow-orange-brown
Co – cobalt sulphate, CoSO4, is pinkish
Ni – nickel chloride, NiCl2, is green
Cu – copper(II) sulphate, CuSO4, is deep blue
Zn – zinc salts such as zinc sulphate, ZnSO4, are usually
colourless and not typical of transition metals (d) Catalytic Properties (1) The metallic elements themselves Many transition metals are used directly as catalysts in industrial chemical
processes and in the anti-pollution catalytic converters in car exhausts. For example iron is used in the Haber Synthesis of ammonia: Nitrogen + Hydrogen ? Ammonia or N2 + 3H2 ? 2NH3 via the Fe catalyst
atoms (2) The compounds of transition metals As well as the metals, the compounds of transition metals also acts as
catalysts. For example manganese dioxide (or manganese(IV) oxide), MnO2, a black powder,
readily decomposes an aqueous solution of hydrogen peroxide: Hydrogen peroxide ? water +
oxygen or 2H2O2 ? 2H2O + O2 via MnO2 as the catalyst