Solveeit Logo
Login

Question

Question: The electronic configuration of \({}_{59}\Pr \)(Praseodymium) is- A.\(\left[ {{}_{54}{\text{Xe}}} ...

The electronic configuration of 59Pr⁡{}_{59}\Pr (Praseodymium) is-
A.[54Xe]4f25d16s2\left[ {{}_{54}{\text{Xe}}} \right]4{f^2}5{d^1}6{s^2}
B.[54Xe]4f15d26s2\left[ {{}_{54}{\text{Xe}}} \right]4{f^1}5{d^2}6{s^2}
C.[54Xe]4f36s2\left[ {{}_{54}{\text{Xe}}} \right]4{f^3}6{s^2}
D.[54Xe]4f35d2\left[ {{}_{54}{\text{Xe}}} \right]4{f^3}5{d^2}

Explanation

Solution

The element Praseodymium has atomic number 5959 .It is an f-block element and comes under lanthanides. The maximum number of electrons that can be filled in s-orbital is 22, p-orbital is 66, d-orbital is 1010 and f-orbital is 1414. The general electronic configuration is-(n−2)f1−14(n−1)d0−1ns2\left( {n - 2} \right){f^{1 - 14}}\left( {n - 1} \right){d^{0 - 1}}n{s^2}.

Complete step by step answer:
We have to find the electronic configuration of Praseodymium. Its atomic number is 5959.
According to the Aufbau principle,
The electrons first occupy the orbitals whose energy is lowest. The electrons enter higher energy orbitals only when lower energy orbitals are completely filled.
The order of increase in energy of orbitals is determined by the (n+l) rule where n is the principal quantum number and l is the azimuthal quantum number.
If two orbitals have equal (n+l) value then electrons will first enter the orbital having a lower n value.
The order of filling of electrons in orbitals is-1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p,6s,4f,5d,6p1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p,6s,4f,5d,6p and so on.
We know the nearest noble gas configuration closest to Praseodymium is Xenon with atomic number 5454. So we will use its abbreviation to indicate the electronic configuration till number 5454. Now we know the general configuration of f-block elements is-(n−2)f1−14(n−1)d0−1ns2\left( {n - 2} \right){f^{1 - 14}}\left( {n - 1} \right){d^{0 - 1}}n{s^2}.
According to this, On putting n=66 we get the ideal configuration should be-[54Xe]4f25d16s2\left[ {{}_{54}{\text{Xe}}} \right]4{f^2}5{d^1}6{s^2} . But the observed electronic configuration is [54Xe]4f36s2\left[ {{}_{54}{\text{Xe}}} \right]4{f^3}6{s^2} . It is because the energies of 4f4f and 5d5d are very close so electrons can exchange their positions.

The correct answer is option C.

Note:
1.Pr is silvery soft metal which tarnishes in air rapidly. Its ions are coloured. Praseodymium is used as following-
2.Its oxides are used to make lenses of goggles for glass makers as it filters out the yellow light which is produced in glass bowing.
3.It forms alloy with magnesium which is used in aircraft engines.