Anirudh Walia is teaching live on Unacademy Plus
1. ALLOTROPIC FORM OF CARBON (a) Diamond G) Three dimensional polymeric structure. (ii) In diamond each carbon is in sp3 hybridized state and is linked to four 1.54 other neighbouring carbon atoms held at the corners of a regular tetrahedron by covalent bonds. (iii) In this structure C-C distance is 1.54 A with a bond angle of 109.5 . (iv) Due to these strong covalent bonds, diamond is the hardest substance Crystal structure of dia having abnomally high melting point (3600 C) and is extremely inert, mond chemically (v) It has very high refractive index (2.5), i.e. light rays are slowed down by the tightly bound electron. (vi) Due to unavailability of mobile electrons it is non-conductor of electricity.
(b) Graphite 6) Unlike diamond, it has a two dimensional laminar structure. (i) The adjacent layers of sheet are held together by weak vander Waal forces (ii) Here each carbon atom is in sp2 hybridised state and is thus attached to three other carbon atoms by three bonds forming a hexagonal planar structure. The fourth electron present in an unhybridised p-orbital of each carbon atom of a hexagonal unit then overlap with each other to form a pi bond. (iv) (v) The C-C bond length in graphite is shorter (1.42 A) than that of diamond (1.54A). 3.4 A Structure of graphite
Amorphous (c) Fullerenes 6) Discovered by smily & robert curl (Noble prize 1996) (i) Fullerene normally contain Cso with smaller quantity of Czo Structure of C6o (0) C6o is also called buckminster fullerene in honour of robert buckminster fuller (i) Shape of Co is Soccer ball& Czo is Rugby ball. (i) Co& Cso having hexagonal & pentagonal unit.
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