Diamond & graphite are allotropes of carbon. Explain how they differ in terms of their molecular structure & why diamond is denser than..graphite?

Crystalline
structure of diamond:

- Each carbon atom is  linked through
four covalences by other four carbon atoms, using a tetrahedral orientation and having a
sp3 hybridization → a crystal diamond seems to be a"Giant
molecule".

- sp3 hybridized carbon atoms form powerful
links, involve all the electrons in connection.

- carbon
atoms have a tetrahedral geometry, which explain the physicochemical properties of
diamond.

- The elementary cell of diamond is
cubic.

Crystalline structure of
graphite:

- Crystal is composed of flat layers of carbon
atoms that are arranged in hexagons, as combs, and they are bound together by atomic
ties, the  parallel planes of carbon atoms are linked by weak bonds, Van der Waals
type;

- carbon atoms are Sp2 hybridized → those three links
made with the three hybrid orbitals are strong, the third 2p orbital of each atom of the
plan remains non-hybridized and contains a single
electron

- all electrons of non-hybridized orbitals of
atoms in a plane are common and mobile and they are belonging to all the atoms in the
plane

- Elementary cell of graphite is of hexagonal
type.