Tiêu đề 5.14TH GROUP FINAL- PHANI SIR.pdf ✅

NISHITH Multimedia India (Pvt.) Ltd., 151 JEE MAINS - CW - VOL - I JEE ADVANCED- VOL - III 14TH GROUP NISHITH Multimedia India (Pvt.) Ltd., 14TH GROUP(IVA GROUP) SYNOPSIS Catenation The property of forming bonds with atoms of the same element or tendency to self linking called catenation. Carbon shows maximum catenation. On moving down the group catenation tendency decreases. This because the strength of C – C bond is very high and in case of other elements, strength of M – M (where M = Si, Ge, Sn, Pb) bond is decreases down the group. Bond BondEnergy (kJmol–1) C – C 348 Si – Si 297 Ge – Ge 260 Sn – Sn 240 Allotropy:  The property of an element to exist in two or more physical forms is called allotropy.  Except Lead, all other IV A group elements show allotropy. Allotropes of carbon:  Crystalline forms: Diamond, Graphite, Fullerenes.  Amorphous forms: Coal, coke, animal charcoal, wood charcoal, lamp black, carbon black, gas carbon, petroleum coke, sugar charcoal.  Lamp black is used in making boot polish, printing ink, paint and black varnish.  Coal is formed in nature as a result of slow decomposition of vegetable matter under the influence of heat, pressure and limited supply of air.  Different forms of coal: (i) Peat (60% carbon) (ii) Lignite(67% carbon) (iii) Bituminous coal(common form) (88% carbon) (iv) Anthracite(purest form of coal) (95% carbon) (Burn without smoke) Diamond:  Diamond is a Crystalline form of carbon  Diamond is the hardest material with high melting point  Diamonds are used as precious stones for jewellery because of their ability to reflect and refract light  Diamond dies are used for drawing thin wires Due to the hardness, diamonds are used for cutting glass, drilling rocks and are used as abrasives.  In diamond each carbon atom is 3 sp hybridized state and is linked to four carbon atoms by single covalent bonds.  In diamond each carbon atom is bonded to four other carbon atoms situated tetrahedrally around it.  Diamond is giant 3D molecule  The C – C distance in diamond is 0 1.54A  Diamonds are bad conductors of electricity as there are no unpaired electrons in them.  The value of a diamond is expressed in terms of a mass unit called carat(1 carat = 200mg of diamond)  Diamonds are insoluble in all solvents  In vacuum diamonds are stable upto 0 1500 C but at 0 1800 2000 C  , they are converted into graphite  The high melting and boiling points of diamond are due to Giant polymer structure with strong covalent bonds  Diamond is chemically inert  Diamond has higher thermal conductivity than graphite.  Total Number of atoms present in a diamond cubic unit cell is 8. Graphite:  Graphite is a Crystalline form of carbon  Graphite is made by Acheson’s process:     2 3C coke SiO SiC 2CO SiC Si C graphite           The allotropic form of carbon formed by thermal