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The number of elements in the first peri...

The number of elements in the first period is only 2. Give reason.

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The first period n=1 ,it is the first energy level and has only 1 s orbital which can accommodate a maximum of 2 electrons hence the number of elements in the first period is only 2.
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SURA PUBLICATION-PERIODIC CLASSIFICATION OF ELEMENTS-ADDITIONAL SHORT ANSWERS
  1. What are representative elements?

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  2. What are metalloids ? Give example.

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  3. The number of elements in the first period is only 2. Give reason.

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  4. The elements Z=117 and 120 have not yet been discovered. In which fami...

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  5. Arrange the following elements in the increasing order of metallic cha...

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  6. Predict the periods and blocks to which each of the following elements...

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  7. Why are noble gases chemically inert?

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  8. Why d- block elements are known as transition element ?

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  9. Rn (Z=86) is the last noble gas discovered . Predict what will be the...

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  10. What are inner transition elements ?

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  11. In terms of electronic configuration what does elements of given peri...

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  12. Write the name and atomic number of the following elements (i) Th...

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  13. First ionisation potential of C- atom is greater than that of B atom ,...

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  14. Atomic number of elements X,Y,Z and A are 4,8,7 and 12 respectivity ....

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  15. Which has the stable electronic configuration : Ni^(2+)orFe^(+3). Wh...

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  16. Define covalent radius.

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  17. Define periodicity.

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  18. Out of Na and Mg , which has higher second ionisation energy?

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  19. Noble gases have maximum ionisation energy. Justify.

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  20. Which of the following species will have the largest and smallest siz...

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