Diamond structure
is ZnS type structure in which carbon
atoms forms a face centred cubic (FCC/CCP) lattice
as well as four out of eight
(50%) or alternate tetrahedral voids are
occupied by carbon atoms. Every atom in this structure is surrounded
tetrahedrally by four other. No discrete molecule can be discerned (identified)
in diamond .the entire crystal is giant molecule a unit cell of which is shown
as below.
Note
: Only those atoms which
form four covalent bond produce a repeated 3D structure using only covalent
bonds.
Lattice of Diamond is ZnS type structure.
(1) C- form FCC/CCP (4-atoms)
(2) C- atoms present at the (50%) alternative
tetrahedral voids (4-atoms)
(3) Total Number of one lattice unit is
eight (8) hence molecular formula of diamond is (C8) (i.e. Z= 8)
(4) Number of C-C bond in lattice cell
is = 4×4= 16
(5) Number of C-C bond per carbon atom
is 16/8=2
(6) The distance between two Corbin atom is dC-C = a√3/4 and the radius of carbon atom = dc-c/2 = rc = a√3/2x4
(8) Packing efficiency (PE = π√3/10= 0.34 or 34%):
(9) Voids = 66 %
Additional
Information:
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