A material exhibits paramagnetism when unpaired electrons exist within its atomic or molecular composition, leading to attraction towards an external magnetic field. We will now analyze each option to identify which one does not possess paramagnetic properties:
- Aluminium: Aluminium's atomic structure contains unpaired electrons, classifying it as paramagnetic.
- Sodium Chloride: Sodium chloride is an ionic compound composed of Na+ and Cl- ions. Each ion possesses a complete electron shell, indicating the absence of unpaired electrons. Consequently, sodium chloride is not paramagnetic; it is diamagnetic.
- Calcium: While elemental calcium does not exhibit strong magnetic properties, the presence of some unpaired electrons renders it weakly paramagnetic.
- Copper Chloride: Copper chloride, particularly in its anhydrous form (CuCl2), features copper ions with unpaired electrons, thus contributing to its paramagnetic characteristics.
In conclusion, the material that is not paramagnetic is Sodium Chloride.