KCET2013Chemistryd and f Block Elements
In a transition series, with increase in atomic-number, the paramagnetism
Options
- Aincreases gradually
- Bdecreases gradually
- Cfirst increases to a maximum and then decreases
- Dfirst decreases to a minimum and then increases
Correct answer
C. first increases to a maximum and then decreases
Step-by-step solution
The paramagnetism of transition elements of a given series increases on moving left to right in a period and attain a maximum value and after that, it goes on decreasing towards the end of period. This is due to the fact that the magnetic moment or paramagnetism is directly related to the number of half-filled d -orbitals. In the beginning, the number of unpaired electrons in d -orbitals increases till the middle of the period (d¹ . to .d⁵ ) . After this, the pairing of electrons occurs in d -orbitals (d⁶ . to .d¹⁰