Electrochemistry

To determine the electronic configurations of Mg⁺² and Cl^– ions, we start by understanding their neutral atoms:

1. Magnesium (Mg): A neutral magnesium atom has an atomic number of 12, so its electronic configuration is 2, 8, 2. When it loses 2 electrons to form Mg⁺², it loses its two outermost electrons, resulting in the configuration 2, 8.

2. Chlorine (Cl): A neutral chlorine atom has an atomic number of 17, making its electronic configuration 2, 8, 7. When it gains one electron to become Cl^–, it adds one electron to its outer shell, resulting in the configuration 2, 8, 8.

Hence, the electronic configurations of Mg⁺² and Cl^– ions are 2, 8 and 2, 8, 8, respectively.

In a NaCl crystal lattice, each Na⁺ ion is surrounded by six Cl^- ions, and each Cl^- ion is surrounded by six Na⁺ ions. The arrangement forms a face-centered cubic (FCC) structure.
This configuration ensures maximum stability through electrostatic attractions between oppositely charged ions, with each ion having a coordination number of 6. Therefore, the coordination number of Na⁺ in a NaCl crystal is 6.