Question

Explain the difference:

a. Diamond and graphite.

b. Crystalline and non-crystalline forms of carbon.

Answer 1

a.

Parameter	Diamond	Graphite
Structure	Eight sides forming double pyramids. Each carbon atom is held firmly in place by four bonds of neighbouring carbon atoms.	Carbon atoms are arranged in flat planes of hexagonal rings, stacked on top of each other.
Nature	Colourless and the hardest substance known	Soft, greyish and slippery to touch
Refractive index	2.5	Opaque
Specific gravity	3.52	2.53
Conductivity	Bad conductor of electricity	Good conductor of heat and electricity
Chemical activity	Chemically inert under ordinary conditions as there are no free electrons available	Slightly more reactive than diamond

b.

Amorphous solids		Crystalline solids
i	They have an irregular shape.	i	They have a definite characteristic geometrical shape.
ii	They have only short-range order in the arrangement of constituent particles.	ii	They have long-range order in the arrangement of constituent particles.
iii	They gradually melt and soften over a range of temperature.	iii	They have sharp and characteristic melting points.
iv	When cut with a sharp-edged tool, they cut into two pieces with irregular shapes.	iv	When cut with a sharp-edged tool, they split into two pieces with plain and smooth newly-generated surfaces.
v	They do not have definite heat of fusion.	v	They have definite and characteristic heat of fusion.
vi	They are isotropic in nature.	vi	They are anisotropic in nature.
vii	They are pseudo solids or super-cooled liquids.	vii	They are true solids.