Step 1: Understand what paramagnetic means. A substance is paramagnetic if it has unpaired electrons in its electron configuration.
Step 2: Identify the complex in question, which is [Co(NH3)6]3+. This means it has cobalt (Co) surrounded by six ammonia (NH3) ligands.
Step 3: Determine the oxidation state of cobalt in [Co(NH3)6]3+. Since the overall charge is +3 and NH3 is neutral, cobalt is in the +3 oxidation state.
Step 4: Find the electron configuration of cobalt in the +3 state. Cobalt (Co) has an atomic number of 27, so its neutral electron configuration is [Ar] 4s2 3d7. In the +3 state, it loses 3 electrons, resulting in [Ar] 3d6.
Step 5: Analyze the 3d6 configuration. In a strong field ligand environment like NH3, the 3d electrons will fill the lower energy orbitals first. For 3d6, this can lead to 4 paired electrons and 2 unpaired electrons.
Step 6: Conclude that since there are unpaired electrons in the 3d6 configuration of [Co(NH3)6]3+, it is paramagnetic.
