Question

What is a differentiating electron? Give an example.

Answer 1

An electron is a negatively charged subatomic particle. It can be either free or bound to the nucleus of an atom. Here, the term “differentiating” indicates something which makes something different from others.

Complete answer:
Let’s completely understand about the differentiating electron.
First, let’s talk about the electron. An electron is a negatively charged subatomic particle which is present either freely or bound to the nucleus of an atom. Differentiating means something which makes something different from others.
The differentiating electron is defined as the last electron that is added while building up the electronic configuration of an atom. It is the electron that differentiates the atom from the one just before it in the periodic table.
Let’s see an example of differentiating electrons.
The electronic configuration of gallium is $[Ar]\,4{s^2}\,3{d^{10\,}}4p$
The element just before gallium in the periodic table is Zinc whose electronic configuration is $[Ar]\,4{s^2}\,3{d^{10\,}}$.
Thus, the differentiating electron of gallium is the electron present in $4p$ subshell.
Another example-
The electronic configuration of sodium is $1{s^2}\,2{s^2}\,2{p^6}\,3{s^1}$
The element just before sodium in the periodic table is neon whose electronic configuration is $1{s^2}\,2{s^2}\,2{p^6}$.
Thus, the differentiating electron of sodium is the electron present in $3s$ subshell.

Note:
In simple words, we can say that the last electron is the orbital. The differentiating electron i.e. the last electron distinguishes between the two entities. There is a difference between differentiating electrons and valence electrons. Valence electrons are electrons which are present in the outermost shell and they take part in chemical bonding whereas differentiating electrons are electrons which give electronic configuration of elements that differ from other elements.