Question

Assign the position of the element having outer electronic configuration.
(i) $n{{s}^{2}}n{{p}^{4}}$ for n=3
(ii) $(n-1){{d}^{2}}n{{s}^{2}}$ for n = 4
(iii) $(n-2){{f}^{7}}(n-1){{d}^{1}}n{{s}^{2}}$ for n = 6, in the periodic table

Answer 1

Different atoms in which the filling of electrons into the orbitals takes place according to the Aufbau principle which is based on Pauli’s exclusion principle and Hund’s rule of maximum multiplicity. The filling of electrons into these orbitals is based on mainly the relative energies of orbitals.

Complete step by step solution:
(i) Given n = 3, so the element belongs to the 3rd period.
From the electronic configuration $n{{s}^{2}}n{{p}^{4}}$, the last electron occupies the p-orbital which belongs to the p-block element and there are four electrons in the p-orbital.
The corresponding group of the element = number of s-block groups ($3{{s}^{2}}$ ) + number of d-block groups + number of p-orbital electrons
= 2 + 10 +4
= 16
Hence, the element belongs to the 3rd period and 16th group of the periodic table and the element is sulfur
($[Ne]3{{s}^{2}}3{{p}^{4}}$ )
(ii) Given n =4, then the element belongs to the 4th period and d-block elements as d-orbital are incompletely filled with 2 electrons in d-orbital.
The corresponding group of the element
= number of s-block groups ($4{{s}^{2}}$ ) + number of d-block groups ($3{{d}^{2}}$)
= 2+2
= 4
Hence, the element belongs to the 4th period and 4th group element.
Therefore, the element is Titanium (Ti) ( $[Ar]3{{d}^{2}}4{{s}^{2}}$)
(iii) for n = 6, $5{{d}^{1}}6{{s}^{2}}$
According to Aufbau’s principle, write in the order of filling the subshells and we know the first 6s will fill then 5d fill.
$6{{s}^{2}}5{{d}^{1}}$
Given, n =6 means the element belongs to the 6ht period which is the highest principal quantum number and the 3rd group. Hence the atomic number is 57.

Note: A quantitatively large number of orbitals can be distinguished by their shape, size, and orientation. A small size orbital means more chance of finding the electron near the nucleus. Atomic orbitals are distinguished by the quantum numbers which are three quantum numbers labeled as n, l, and m.