Given below are some elements of the modern periodic table, atomic, number of the element is given in the parentheses

CBSE Class 10 CBSE Class 10 Science
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Given below are some elements of the modern periodic table, atomic, number of the element is given in the parentheses: A (4), B (9), C (14), D (19), E (20).

  1. Select the element that has one electron in the outermost shell. Also write the electronic configuration of this element.
  2. Which two elements amongst these belong to the same group? Give reason for your answer.
  3. Which two elements amongst these belong to the same period ? Which one of the has bigger atomic radius?
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  1. D (19): 2, 8, 8, 1 ; Element is Potassium.
  2. A (4): 2, 2 ; E (20) : 2, 8, 8, 2
    Elements A and E belong to same group because both have 2 valence electron.
  3. A (4): 2, 2 ; B (9) : 2, 7.
    Thus, elements A and B both belong to same period because both have two shells.