Question

How many unpaired electrons are there in tungsten?

Answer 1

To calculate the unpaired electrons in an element first we should have an idea about the shells, orbitals and the number of electrons each can shells and orbitals can accommodate. The atomic number of a given element is 74.

Complete answer:
In the question, it is asked how many unpaired electrons are available. Before going into the solution for the question let us briefly discuss the atomic structure.
As we know that an atom consists of a massive nucleus and the electrons are distributed outside the nucleus. The nucleus possesses both protons and neutrons and the electrons are distributed in various shells of the atom.
Each atom consists of various shells like K shell, M shell etc. And each shell will have subshells and each sub-shells will have various orbitals in them.
All the orbitals will have the capacity to accommodate two electrons only. And the two electrons occupied will have opposite spin.
Now let us solve the question given. Here we are concerned about the number of unpaired electrons present. To solve the question first we have to know the atomic number of the element.
The atomic number of tungsten (W) is 74.So we know that there are 74 electrons in the atom, since the atomic number is equal to the number of protons or electrons present in the atom.
Now distribute the electrons in various orbitals according to the increasing order of their energy.
And such a way of distributing electrons is called an electronic configuration of the element.
$W=1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{10}}4{{s}^{2}}4{{p}^{6}}4{{d}^{10}}4{{f}^{14}}5{{s}^{2}}5{{p}^{6}}5{{d}^{4}}6{{s}^{2}}$
$W=\left[ Xe \right]4{{f}^{14}}5{{d}^{4}}6{{s}^{2}}$
The s subshell can accommodate 2 electrons, p subshell can accommodate 6 electrons and d subshell can accommodate 10 electrons.
So if we analyze the above configuration of W, there are four unpaired electrons since other orbitals are completely filled and d subshell has 5 orbitals and can accommodate 10 electrons but only 4 are filled and the orbitals are filled with electrons in such a way that all the orbitals will be filled singly first and then the sixth electron will start the pairing.
Hence we can conclude that in Tungsten, there are four 5d electrons.

Note:
The electrons are filled in each orbitals by obeying all the rules associated with Pauli's exclusion principle, Afbau principle and Hund's rule of multiplicity. And we should be thorough with the increasing energy series of the orbitals since for writing the electronic configuration of the element to calculate the unpaired number of electrons present.