4.6 Transition Elements

Physical properties
■ Transition elements

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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

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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

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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

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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

← 4.5 Elements in Period

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