Thursday, 8 January 2015

4.6 Transition Elements

Physical properties
■ Transition elements

Metals which are placed between Group 2 and Group 13 in Periodic Table of Elements.
■ Physical properties:

Elements Proton number Melting point(℃) Boiling point (℃) Oxidation number Oxides
Sc 21 1400 3800 3 Sc2O3
Ti 22 1720 3200 2, 3, 4 TiO2
Ti2O3
V 23 1710 3500 2, 3, 4, 5 VO
VO2
V2O3
V2O5
Cr 24 1900 2480 2, 3, 6 CrO
CrO3
Cr2O3
Mn 25 1250 2000 2, 3, 4, 7 MnO
MnO2
Mn2O3
Mn2O7
Fe 26 1530 2730 2, 3 FeO
Fe2O3
Co 27 1490 2900 2, 3 CoO
Co2O3
Ni 28 1450 2840 2, 3 NiO
Ni2O3
Cu 29 1083 2350 1, 2 CuO Cu2O
Zn 30 419 907 2 ZnO

The physical and chemical properties of the elements are similar and do not change much across the period.
■ All transition metals are

not reactive or less reactive compare to alkali metals.

harder with higher melting and boiling point than the alkali metals.

shining surface, malleable, ductile, high tensile strength,

good conductors of heat and electricity.
■ This video contains information about the transition elements
Special features of transition metals
■ Coloured ions or compounds

They form ions, compounds and solution which are coloured.
Element Ion Colour
Chromium Cr3+ Green
CrO42- Yellow
Cr2O72- Orange
Manganese Mn2+ Pale pink
MnO4- Purple
Iron Fe2+ Pale green
Fe3+ Yellowish brown
Cobalt Co2+ Pink
Nickel Ni2+ Green
Copper Cu2+ Blue (CuSO4)
Green (CuCO3)
■ Complex ions

form complex ions which are coloured, such as
Hexacyanoferrate(II) ion, (Fe(CN)6)4-
Hexacyanoferrate(III) ion, (Fe(CN)6)3-
■ Oxidation number which are different

All transition elements except scandium and zinc have more than one oxidation number.

Elements Sc Ti V Cr Mn Fe Co Ni Cu Zn
Oxidation number 3 2, 3, 4 2, 3, 4, 5 2, 3, 6 2, 3, 4, 7 2, 3 2, 3 2, 3 1, 2 2


■ Act as catalysts

Transition metals are good catalysts. A specific catalyst is used for a specific reaction, as in:
Process Catalyst Produce
Haber Iron fillings Ammonia
Contact Vanadium (V) oxide Sulphuric acid
Ostwald Platinum Nitric acid
Hydrogenation Nickel Margarine


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