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Classification of Elements and Periodicity in Properties — Chemistry STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 ScienceChemistryClassification of Elements and Periodicity in Properties5 Marks
Question
Which elements have the following electronic configurations? (Use only the periodic table.)
  1. 1s2, 2s2, 2p5
  2. [Ar]4s2, 3d10, 4p1
  3. [Xe]6s2
  4. [Xe]6s2, 5d1, 4f7
  5. [Ar]4s1, 3d10 (exception to rules)
✓

Answer

  1. The outer electronic configuration of 1s2, 2s2, 2p5 is 2s2, 2p5. Therefore, this element is a p-block element and belongs to the second period and group 17. Thus, the element is fluorine, F.
  2. The outer electronic configuration of [Ar]4s2, 3d10, 4p1 is 4s2 4p1, therefore, it is a p-block element. It belongs to the fourth period and 13 group. Therefore, the element is gallium, Ga.
  3. The outer electronic configuration of [Xe]6s2 is 6s2, therefore, it is a s-block element and belongs to the sixth period and group 2 of the periodic table.

Therefore, the element is barium, Ba.

  1. In the electronic configuration [Xe]6s2, 5d1, 4f7 the electrons are in 4f shell, therefore, it is a f-block element and belongs to the sixth period and third group therefore, the element is gadolinium, Gd.
  2. The outer electronic configuration of [Ar]4s1, 3d10 is 4s1, 3d10, therefore, it is a d-block element and belongs to the fourth period and group 11. Therefore, the element is copper, Cu.

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