Question

Write the electronic configuration of the cation $F{e^ + }$.

Answer 1

To answer this question, you should know about the atomic number of iron, $Fe$ and in which period it is present in the periodic table. Here, $Fe$ has a positive charge of $+ 1$. This $+ 1$ charge is its oxidation number. Oxidation number indicates the number of electrons gained or lost.

Complete answer:
We know that the atomic number of the given metal i.e. iron $(Fe)$ is $26$. It is a transition metal and it belongs to the d- block element. The electronic configuration of the d- block element $(n - 1){d^{1 - 10}}\,ns$. The outermost shell of iron $(Fe)$ is $3d\,\,4s$ as it is present in the third period and eighth group in the periodic table.
The atomic number of iron $(Fe)$ is $26$
The electronic configuration of iron $(Fe)$is $[Ar]\,3{d^6}\,4{s^2}$
Here, iron $(Fe)$ has a positive charge of $+ 1$ i.e. cation $F{e^ + }$ which indicates that it loses one electron. $Fe$ is a neutral element. When it loses its one electron, it forms a cation $F{e^ + }$
Therefore, the electronic configuration of cation $F{e^ + }$ is $[Ar]\,3{d^6}\,4{s^1}$.

Note:
The outermost shell of the element is determined by identifying at which block the element is present. For example- here, $Fe$ is a d-block element which indicates that its outermost shell is $3d\,\,4s$. Similarly, the number of electrons present in the outermost shell is indicated by its group number. Also, the period in which an element is present tells about the principal quantum number of the shell. Remember, the oxidation number indicates the number of electrons lost or gained. The positive charge indicates the loss of an electron whereas the negative charge indicates the gain of an electron. If there is no charge present, it indicates that it is a neutral element.