Question

What is the electronic configuration of selenium ions in excited state?

Answer 1

We have to remember that the excitation of electrons takes place from ground state to excited state. When an electron gets excited from ground state some energy is released. Excited state always has higher energy than the ground state. Noble gas configuration has filled orbitals and it has complete octet.

Complete answer:
We have to remember that the selenium is an element that has atomic number $34$ and belongs to group$16$. It has an atomic symbol $Se$. It has two electrons less to attain a stable electronic configuration or noble gas configuration.
Electronic configuration of $Se$ in ground state: $\left[ {Ar} \right]3{d^{10}}4{s^2}4{p^4}$, the electrons in the outermost shell or valence shell is $6$. That means only two electrons less to attain noble gas configuration.
To know the electronic configuration of $Se$ in excited state: $\left[ {Ar} \right]3{d^{10}}4{s^2}4{p^3}5{s^1}$ when an electron gets excited from ground state to excited state extra shell is added and the electron from outermost shell that is p orbital moves to next $s$ orbital giving $3$ electrons in $p$ shell and $1$ electron in next $s$ orbit.
One $4p$ electron is now transferred to $5s$orbital. $Se$ Element is non-metal but it has certain properties that are intermediate between metals and nonmetals that come under the category of metalloids. It’s chemical properties are similar to arsenic. It has several isotopes and it belongs to p block elements. The commonly used oxidation states are $+ 2$ and $- 2$.

Note:
Since selenium belongs to p block elements and it has its chemical properties intermediate between metals and non-metals thus they are known as metalloids and behave as semiconductors and are good conductors of heat and electricity but not as that much of conductors.