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CHEMISTRY (CHAPTER-THE P-BLOCK ELEMENTS)


                    SUBTOPIC - GR.14 ELEMENTS ( CARBON FAMILY )TRENDS IN

                    ATOMIC PROPERTIES,  PHYSICAL PROPERTIES, CHEMICAL
                    PROPERTIES, ANOMALOUS PROPERTIES OF CARBON,  ALLOTROPES

                    OF CARBON, USES OF CARBON

                    TRENDS IN ATOMIC PROPERTIES Group 14 elements are carbon (C) ,

                    silicon (Si), germanium (Ge), tin (Sn) and lead (Pb) .

                     i.Electronic Configuration: The general outer electronic

                    configuration of these elements is ns2np2.

                    ii.Atomic Radii: From Si to Pb a small increase in radius is observed.
                    This is due to the presence of completely filled d and f orbitals in

                    heavier members.

                    iii.Ionization Enthalpy:Small decrease in ΔiH from Si to Ge to Sn and

                    slight increase in ΔiH from Sn to Pb is the consequence of poor
                    shielding effect of intervening d and f orbitals and increase in size of

                    the atom.

                    iv. Electronegativity :The electronegativity values  from Si to Pb are

                    almost the same, due to poor shielding effect of d and f electrons.

                    TRENDS IN PHYSICAL PROPERTIES:Carbon and silicon are non-metals,

                    germanium is a metalloid, whereas tin and lead are soft metals with
                    low m.p.The m.p of Sn is lowest in group 14 due to weak metallic

                    bond.
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