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 $\left(d^{1}\right.$ to $\left.d^{5}\right)$. After this, the pairing of electrons occurs in $d$-orbitals $\left(d^{6}\right.$ to $\left.d^{10}\right)$.
Thus, in a given transition series, with increases in atomic-number, the paramagnetism first increases to a maximum and then decreases.