Question

What is the ground state electron configuration for Ru2+?

Answer 1

Electronic configuration: The distribution or arrangement of electrons of a molecule or an atom in molecular or atomic orbitals.

Ground state electron configuration: The distribution of electrons of an atom or molecule around the nucleus with lower levels of energy.

Now, $Ru$ stands for Ruthenium with atomic number 44. It is a metal and thus, has ability to lose electrons and, becomes positively charged ion.

One can write the electronic configuration with the help of atomic number and Afbau principle, Pauli exclusion principle etc.

Ground electronic Configuration is as follows:

$Ru = s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{1}4d^{7}$

Soft Hand notation: $[Kr]4d^{7}5s^{1}$

Now, when ruthenium loses two electrons then it becomes $Ru^{+2}$, thus electron configuration becomes

Soft Hand notation: $[Kr]4d^{6}$

The ground state electronic configuration of Ruthenium is $[Kr]4d^{7}5s^{1}$ and when it loses two electrons, then electronic configuration becomes $[Kr]4d^{6}$ ( $Ru^{+2}$)

Answer 2

The correct answer to this question is "[Kr]4d^6." 

the ground state electron configuration for Ru2+ is "[Kr]4d^6." 

As you know, the ground state electron configuration for Ru2+ is Ru. However, Ru is a special case; its electron configuration is [Kr]4d75s1.