The ground state electron configuration of cobalt atom. How many paired electrons does this element have and is the atom paramagnetic or diamagnetic?
The Correct Answer and Explanation is:
The electron configuration of a cobalt (Co) atom in its ground state is:
Co:1s22s22p63s23p63d74s2\text{Co}: 1s^2 2s^2 2p^6 3s^2 3p^6 3d^7 4s^2Co:1s22s22p63s23p63d74s2
To break this down:
- 1s^2 2s^2 2p^6 3s^2 3p^6: These represent the first two energy levels, where all the orbitals are fully filled, meaning no unpaired electrons in these shells.
- 3d^7: This shows that there are seven electrons in the 3d orbital. The 3d orbitals can hold a maximum of 10 electrons.
- 4s^2: This represents two electrons in the 4s orbital.
Now, to answer the specific questions:
Paired Electrons:
- In the 3d orbital (where there are 7 electrons), some electrons will be paired, while others will be unpaired.
- The first five 3d orbitals (degenerate orbitals) will contain a maximum of 5 unpaired electrons, because electrons fill orbitals singly first to minimize repulsion (Hund’s Rule).
- The remaining two electrons will pair up in two of the 3d orbitals.
Therefore, in total, there are 2 paired electrons in the 3d orbital. Additionally, there are 2 paired electrons in the 4s orbital. So, cobalt has 4 paired electrons overall.
Paramagnetic or Diamagnetic:
- Paramagnetism arises from the presence of unpaired electrons. Since cobalt has unpaired electrons in the 3d orbital (specifically, 3 unpaired electrons), it is paramagnetic.
Conclusion:
- Cobalt has 4 paired electrons in total.
- The atom is paramagnetic, as it has unpaired electrons in its 3d orbitals.
