How would you account for the irregular variation of ionisation enthalpies (first and second) in the first series of the transition elements?
Ionization enthalpies are found to increase in the given series due to a continuous filling of the inner $d$ -orbitals. The irreqular variations of ionization enthalpies can be attributed to the extra stability of configurations such as $d^{0}, d^{5}, d^{10}$. since these states are exceptionally stable, their ionization enthalpies are very high.
In case of first ionization energy, $Cr$ has low ionization energy. This is because after losing one electron, it attains the stable configuration $\left(3 d^{5}\right) .$ On the other hand, $Z n$ has exceptionally high first ionization energy as an electron has to be removed from stable and fully-filled orbitals $\left(3 d^{10} 4 s^{2}\right)$
Second ionization energies are higher than the first since it becomes difficult to remove an electron when an electron has already been taken out. Also, elements like $Cr$ and $Cu$ have exceptionally high second ionization energies as after losing the first electron, they have attained the stable configuration $( Cr ^{+}: 3 d^{5} $ and $ Cu ^{+}: 3 d^{10})$. Hence, taking out one electron more from this stable configuration will require a lot of energy.
Which one of the following compounds is not coloured
German silver is an alloy of $Cu$ with
A nitrate when mixed with common salt gives a white precipitate which is soluble in dilute $N{H_4}OH$. It is the nitrate of
Which ion has maximum magnetic moment
Which of the following statements are correct?
$(A)$ The $M ^{3+} / M ^{2+}$ reduction potential for iron is greater than manganese
$(B)$ The higher oxidation states of first row $d$ block elements get stabilized by oxide ion.
$(C)$ Aqueous solution of $Cr ^{2+}$ can liberate hydrogen from dilute acid.
$(D)$ Magnetic moment of $V ^{2+}$ is observed between $4.4-5.2\,BM$
Choose the correct answer from the options given below: