Question

Assign the position of the element having outer electronic configuration

1. \(ns^ 2 np^ 4\) for \(n\) = \(3\) 
2. \((n - 1)d^ 2 \;ns^ 2\) for \(n\) =\( 4\), and 
3. \((n - 2) f ^7 (n - 1)d ^1 ns^ 2\) for \(n\) = \(6\), in the periodic table.

Answer 1

Assignment of position in the periodic table:

The position of an element in the periodic table is determined from its outer electronic configuration, which gives information about its period, group, and block.

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(i) Outer electronic configuration: ns² np⁴, n = 3

Given configuration:
3s² 3p⁴

• The highest value of n is 3, so the element belongs to the 3rd period.
• The last electron enters the p-subshell, so it belongs to the p-block.
• Number of valence electrons = 2 + 4 = 6, so it belongs to Group 16.

Position: 3rd period, Group 16, p-block
Element: Sulphur (S)

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(ii) Outer electronic configuration: (n − 1)d² ns², n = 4

Given configuration:
3d² 4s²

• The highest value of n is 4, so the element belongs to the 4th period.
• The last electron enters the d-subshell, so it belongs to the d-block.
• Group number = (number of d electrons + number of s electrons) = 2 + 2 = 4.

Position: 4th period, Group 4, d-block
Element: Titanium (Ti)

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(iii) Outer electronic configuration: (n − 2)f⁷ (n − 1)d¹ ns², n = 6

Given configuration:
4f⁷ 5d¹ 6s²

• The highest value of n is 6, so the element belongs to the 6th period.
• The presence of f-electrons indicates that the element belongs to the f-block.
• Elements with 4f electrons are lanthanides.

Position: 6th period, f-block (lanthanide series)
Element: Gadolinium (Gd)

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Conclusion:

Thus, the positions of the given elements in the periodic table can be correctly assigned using their electronic configurations.