Here is a worked example problem showing how to tell whether an element is paramagnetic or diamagnetic based on its electron configuration.
ProblemWhich of the following elements would be expected to be paramagnetic? Diamagnetic?
He, Be, Li, N
SolutionAll of the electrons are spin-paired in diamagnetic elements so their subshells are completed, causing them to be unaffected by magnetic fields. Paramagnetic elements are strongly affected by magnetic fields because their subshells are not completely filled with electrons. So, to determine whether the elements are paramagnetic or diamagnetic, write out the electron configuration for each element.
He: 1s2 subshell is filled
Be: 1s22s2 subshell is filled
Li: 1s22s1 subshell is not filled
N: 1s22s22p3 subshell is not filled