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  Inorganic Chemistry

Atomic Radii and Electronegativity Of Carbon Family :

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Atomic radii

(i) Both atomic radii and atomic volume increases gradually on moving down the group due to the effect of extra shell being added from member to member.

 

         C   Si              Ge        Sn          Pb 
Atomic radius (pm) 0.77 111 122    141 144
 Atomic volume (ml) 3.4                    11.4 13.6 16.3  18.27

(ii) The atomic radii of group 14 elements are than their corresponding group 13 elements due to increase in nuclear charge in the same period.

(iii) Some of the ionic radii involving six co-ordination of these group elements are given below,

         C   Si              Ge        Sn          Pb 
Ionic radius (M2+) in pm - -  73 118  119
Ionic radius (M++) in pm -                  40 53 69 78

Electronegativity : The electronegativity decreases from C to Si and then becomes constant.

         C   Si              Ge        Sn          Pb 
Electronegativity on pauling scale  2.5          1.8   1.8  1.7    1.6

The electronegativity from silicon onwards is almost is almost constant or shows a comparatively smaller decreases due to screening effects of d10 electrons in elements from Ge onwards.

 

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