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Transition Elements And Its Properties
- Transition metal is a block of metallic elements in between Groups 2 and 13 in the Periodic Table.
- They are much less reactive than the alkali metals.
- They do not react as quickly with water or oxygen as alkali metal.
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Some General Physical Characteristics
- All transition elements are metals. Therefore they have the all the physical properties of metal such as:
- high melting point and boiling point
- hard,
- high density,
- high electrical conductivity,
- high tensile strength ,
- shinny surfaces,
- ductile
- malleable ,
High Melting Point and Boiling Point
- The bond between atoms of metal is called metallic bond and usually it is a very strong bond.
- Thus all the transition metals have high melting points and boiling points.
- For example: iron melts at 1535°C and boils at 2750°C.
- Mercury is a transition metal, but with unusual low melting point ( − 39oC).
Special Properties of Transition Elements
Form Coloured Compounds and Ions in Solute
- Transition elements tend toform coloured compounds either in solid form or dissolved in a solvent.
- Table below shows the colours of some aqueous solutions of ions of transition elements.
Ion | Colour |
Fe2+ | Light green |
Fe3+ | Brown |
Ni2+ | Green |
Cr3+ | Green |
Mn2+ | Pink |
Cu2+ | Blue |
Co2+ | Pink |
MnO4- | Purple |
CrO42- | Yellow |
Cr2O72- | Orange |
Catalytic Properties
- Transition elements or their compounds have catalytic properties.
- A catalyst is a substance that speeds up a reaction but it itself does not change chemically after a reaction.
- Many transition metals are used directly as catalysts in industrial chemical processes.
- Table below shows the uses of transition elements or their compounds as catalysts in industries .
Transition Elements or Its Compound | Uses |
Platinum and rhodium | Used in the catalytic converters in car exhausts to reduce the emission of carbon monoxide and nitrogen |
Platinum | Ostwald Process in the manufacture of nitric acid. |
Nickel | Catalyst for 'hydrogenation' in the margarine industry.This process converts unsaturated vegetable oils into higher melting saturated fats. |
Iron powder | Haber Process in the manufacture of ammonia. Iron catalyzes the reaction between nitrogen and hydrogen gas to produce ammonia. |
Vanadium(V) oxide | Contact Process in the manufacture of sulphuric acid . In Contact Process, Vanadium(V) oxide catalyzes the oxidation of sulphur dioxide to sulphur trioxide. |
Variable Oxidation State
- A transition metal can have a variable oxidation state, which means it can form more than one ion.
- Table below shows the ions of transition elements that have
for example, iron(II), Fe2+ and iron(III) Fe3+; copper(I), Cu+ and copper (II) Cu2+.
Forming Complex Ions
- Transition elements can form complex ions.
- A complex ion is a polyatomic ions (positive or negative) consisting of a central metal ion with other groups bonded to it.
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