Metals and Non-Metals

IONIC BOND -

The chemical bond formed by the transfer of electrons from one atom to another.

COVALENT BOND -

The chemical bond formed by sharing of electrons between two atoms .It takes place between atoms of two non-metals or between atoms of same element.

H.  +  : .Cl ::  → H ::Cl::
1        2, 8, 7       (2) (2, 8, 8)

OCCURRENCE OF METALS :-

  • Earth’s crust –major source.
  • Reactive metals do not occur as free elements in nature.
  • Less reactive metals found in free state.
  • Copper and silver are found in free as well as combined state.
  • All  metals placed above copper are found in form of their compounds

( sulphides, oxides or carbonates)

Minerals  and Ores :-

The natural materials in which the metals or their compounds are found in the earth. Those minerals from which the metals can be extracted conveniently and profitably are called ores.
“All ores are minerals but all minerals are not ores.”

EXTRACTION OF METALS :- To obtain metal from its ore.

Metallurgy :-

The various processes involved in the extraction of metals from their ores, and refining .
Steps in extraction :-

1. Concentration / enrichment of ore.

2. Conversion of concentrated ore into metal

3. Refining (purification) of impure metal

1. Concentration of ore -

    Ore contains large amount of sand and rocky material .
     Gangue -  The unwanted impurities like sand, rocky material, earthy particles, limestone, mica , etc., present in an ore.
    The processes used for removing it  depend on the physical or chemical properties of the ore and gangue.

2. Conversion of concentrated ore into metal –

For this metals are grouped into 3 categories

i) Highly reactive

ii) Moderately reactive

ii) Less reactive

Carbon can reduce the oxides of zinc and metals below it to form metals.

K
Na
Ca
Mg
Al
Electrolysis of molten chloride or oxide
Zn
Fe
Pb
Cu
Reduction of oxide with carbon
Cu
Hg		 Heating sulphide in air

Ag
Au
Pt

 Found in native state as metals

 

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