Question

The position of eight elements in the Modem Periodic Table is given below where atomic numbers of elements are given in the parenthesis.; (i) Write the electronic configuration of Ca.; (ii) Predict the number of valence electrons in Rb.; (iii) What is the number of shells in Sr?; (iv) Predict whether K is a metal or a non-metal.; (v) Which one of these elements has the largest atom in size?; (vi) Arrange Be, Ca, Mg and Rb in the increasing order of the size of their respective atoms.(All India - 2016)

Answer 1

Answer:

Explanation:

[i] the electronic configuration of Ca is

               ca

           2,8,8,2

[ii]        

        rubidium

             2,8,18,8,1

 hence the valency no. of electrons will be 1

it is in the 1st group.

[iii]            strontium ha 5 shells

         strontium

              2,8,18,8,2

[iv]  K will be a metal as it has only one valence electron . hence it has the tendency to give away electrons making it electropositive.

[v] rubidium will have the largest size as it is in the 1st group and lowest in it

[vi]  be> mg> ca> rb

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