The electron configuration of calcium ion (Ca+1) has its atomic number 20. It has 2 unpaired electrons and is paramagnetic.
The Correct Answer and Explanation is:
Correct Answer:
The electron configuration of a calcium ion with a +1 charge (Ca⁺) is:
[Ar] 4s¹
Ca⁺ has 1 unpaired electron and is paramagnetic.
Explanation:
Calcium (Ca) is an alkaline earth metal with atomic number 20. In its neutral (uncharged) state, the electron configuration of calcium is:
Ca: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
or, using noble gas shorthand:
[Ar] 4s²
This configuration reflects the filling of electrons according to the Aufbau principle, Hund’s rule, and the Pauli exclusion principle. The two electrons in the outermost 4s orbital are the valence electrons and are the most loosely bound.
When calcium loses one electron to form a Ca⁺ ion (not the common +2 oxidation state), the electron is removed from the 4s orbital, which is the highest energy orbital in the atom.
Thus, the electron configuration of Ca⁺ becomes:
[Ar] 4s¹
The 4s¹ configuration has one unpaired electron, since there is a single electron in the 4s orbital without a partner of opposite spin.
Because of this unpaired electron, the Ca⁺ ion is paramagnetic. Paramagnetism refers to the tendency of species with unpaired electrons to be attracted to a magnetic field. Unpaired electrons generate a magnetic moment, and the ion interacts with external magnetic fields.
In contrast, a Ca²⁺ ion (which is the more stable and commonly occurring form in nature) has the configuration [Ar], with no unpaired electrons, making it diamagnetic.
Therefore, Ca⁺ with its [Ar] 4s¹ configuration has 1 unpaired electron and exhibits paramagnetic behavior due to the presence of that unpaired electron
