In this article, we should discuss the Ni2+ electron configuration, Ni2+ magnetic behavior, Ni2+ complex formation, and detailed fact.
The position of Ni in the periodic table is the 4th period and group 10th element. It is a d block element and transition metal element (partially or fully filled d electrons in the ground state ) with atomic number 28. Ni2+ is a dication of Ni having 26 electrons. Ni has fully filled d electrons but Ni2 has 8 d electrons. It is 3d series.
Some facts about Ni2+
Ni2+ electron configuration is 1s22s22p63s23p63d84s2. The atomic radious of Ni2+70 pm. Ni2+ having fcc (face centre cubic ) crystal structure.
From the electronic configuration, it is evident that Ni2+ has 8 d electrons, so it is often referred to as a 3d8 electron element. So Ni2+ has more d electrons so it has a high affinity to bing π- acidic ligand in organometallic chemistry like PPh3, CO, CN, etc.
Ni is a moderately electropositive transition element, so Ni2+ is formed due to the loss of two electrons and the standard electrode potential for this process is positive.
Ni – 2e– = Ni2+ , ΔE0= +0.24V
Ni2+ electron configuration
As discussed, earlier Ni2+ belongs to the 3d block element so it has 8 d electrons in the outermost shell. The total number of electrons in Ni2+ is 26. They are distributed as follows,
From the above Ni2+ electron configuration it is shown that 8 electrons are present in the 3d shell and 2 electrons are present in the 4s shell. But due to exchange energy and according to the Aufbau principle electrons first filled in the 4s orbital and donated from the 3d orbital. So, the valence shell is a 3d shell for transition elements. So, the octet of Ni2+ is not completed as two electrons missing from its valence shell, so it is more reactive than Ni and participates in many reactions.
How many electrons does Ni2+ have ?
The number of electrons in Ni2+ is 26.
1s orbital has two electrons, 2s and 2p have 8 electrons, 3s,3p, and 3d have 16 electrons and 4s orbital has the rest of two electrons. Individually 3d orbital has 8 electrons, so Ni2+ has 8 d electrons which are valence shell electrons and participate in different reactions.
How many protons are in Ni2+ ion ?
The number of proton and electrons are the same for every element.
For Ni, the total number of electrons is 28 (1s22s22p63s23p63d104s2 ,ni2+ electron configuration), so the number of protons in Ni is also 28 as the Ni is neutral and proton and electrons are cancel out their charge. But in Ni2+ there is a shortage of two electrons but the protons are reminded the same so the charge over Ni2+ is +2 for two extra protons cause the electrons are 26 but the number of protons is still 28.
Ni2+ molar mass
The Molar mas of Ni2+ is 58.69 g/mol.
We know the molar mass is equal to the molecular mass of that element divided by its own number of substances. For Ni, the molecular mass is 58.69 g. The number of substances is 1 here. So, the molar mass of Ni is 58.69 g/mol. For Ni2+ the molecular weight is as same as Ni, cause Ni2+ is only the dication of Ni, so no change in mass and there is no effect in the number of cations and anions in molar mass. So, the molar mass of Ni2+ equal to Ni is 58.69 g/mol.
CFT of Ni2+
CFT or Crystal Filed Theory is only applicable for transition or inner transition elements. Here we consider only the outermost electrons that is d electrons only.
For CFT we only consider the outermost shell that is only d electrons. First of all, the electrons in d electrons are distributed in five subsets and then arrange in order to their energy. The electrons are filled according to Hund’s rule and Pauling’s exclusion principle. From Ni2+ electron configuration,
The electrons in the subset are divided according to their energy to t2g and eg (in the octahedral field). T2g set contains dxy, dyz, dzx, and eg set contains dx2–y2 and dz2. From the above diagram for Ni2+ ion six electrons are present in the t2g set of orbital and two electrons are present in the eg set of the orbital.
Now we calculate the CFSE (Crystal filed stabilization energy), for Ni2+ ion in an octahedral field.
The energy of each t2g orbital is -0.4Δ0 and the energy of each eg orbital is -0.6Δ0.
So, the total CFSE for Ni2+ = (-0.4Δ0*6)-( -0.6Δ0*2)
= -1.2 Δ0
From this CFT, we can easily calculate the number of unpaired electrons, and the magnetic behavior of Ni2+.
Number of unpaired electrons in Ni2+
The number of unpaired electrons for Ni2+ is two.
From the box diagram and Ni2+ electron configuration, it is evident that among 8 electrons of Ni2+ in d orbital, six electrons are paired in dxy, dyz, dzx, orbitals, and two electrons remain in unpaired form in dx2–y2 and dz2orbital. So, the number of unpaired electrons in Ni2+ is two. The filling of electrons according to Hund’s rule, that is first each subset filled via single electrons only, after filling all the subset then other electrons come to pair up.
Magnetic behavior of Ni2+
The magnetic behavior of any element is dependent on the number of unpaired electrons present.
From the box diagram as well as Ni2+ electron configuration, it is shown that Ni2+ has two unpaired electrons. So, it is paramagnetic in nature.
The magnitude of the magnetic moment can be calculated by the formula, [n(n+2)]1/2, where n is the number of unpaired electrons. For Ni2+ the number of unpaired electrons is 2.
So, the magnetic moment of Ni2+ is [(2(2+2)]1/2 = 2.82 B.M.
Ni(II) complex is paramagnetic but Ni(O) complex is diamagnetic. why?
From Ni2+ electron configuration, in Ni(II) complex the oxidation number of Ni is +2, 8 electrons present in the d orbital. Where in Ni(0) complex, Ni is a zerovalent state, and hence it is the d10 system that is d orbitals are fully filled.
Hence the complex of Ni(0) has no unpaired electrons unlike the case of the Ni(II) complex and hence it is diamagnetic in nature.