Question

How do you write the electron configuration for ${\mathrm{Ni}}^{2+}$?

Answer 1

Electronic configuration:-

• Electron configuration of an element shows us how the electrons are distributed in its atomic orbitals.
• The electron configurations of atoms follow a standard notation in which all the atomic subshells that contain electrons (with the number of electrons they hold written in superscript) are placed in a certain sequence.
• For example, the atomic number of Sodium is 11 and its electron configuration is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^1$.

Aufbau principle:-

• The Aufbau principle states how the electrons are filled in their atomic orbitals of an atom that is in its ground state.
• The principle states that electrons are filled into the atomic orbitals in the increasing order of the orbital energy level.
• According to the Aufbau principle, the available atomic orbitals which have the lowest energy levels are occupied before those which have higher energy levels.
• A diagram is given below which illustrates us the order in which atomic orbitals are filled:

• Here, $‘\mathrm{n}’$refers to the principal quantum number whereas, $‘\mathrm{l}’$refers to the azimuthal quantum number.
• When $\mathrm{l}=0$ it is the s-orbital, when $\mathrm{l}=1$ it is the p-orbital, when $\mathrm{l}=2$ it is the d-orbital and when $\mathrm{l}=3$ it is the f-orbital

Electronic configuration of Nickel:-

• Atomic number of Nickel is 28, that is Nickel has a total of 20 electrons.
• Since 1s orbital can hold a maximum of 2 electrons, so first 2 electrons will fill the 1s orbital, and the next 2 electrons will fill the 2s orbital.
• The next six electrons of Calcium will go in the 2p orbital, as the p orbital can hold up to six electrons.
• The 2p orbital will be completely filled with six electrons and after that, the next two electrons will move up to fill the 3s orbital.
• Similarly in the same fashion, the next 6 electrons will fill up the 3p orbital.
• Again the, 2 electrons will be placed in the 4s orbital.
• And lastly, the remaining 8 electrons will be placed in the 3d orbital, as the d-orbital can accommodate up to 10 electrons.
• Therefore, the electronic configuration of Nickel in the ground state is$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{2}3{\mathrm{d}}^8$.
• But here it is asked to write the electronic configuration of ${\mathrm{Ni}}^{2+}$, which means it has 2 electrons less.
• Now, these 2 electrons will be removed during a reaction from the outermost 4s orbital, rather than the 3d orbital.
• Now the new electronic configuration of ${\mathrm{Ni}}^{2+}$is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^8$
• This filling up of the orbitals with electrons is according to the Aufbau principle.

Therefore, the electronic configuration of ${\mathrm{Ni}}^{2+}$according to the Aufbau principle can be written as$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^8$.