NaCl crystallizes in a cubic unit cell with Cl^- ions on each corner and each face.How many Na⁺ and Cl^- ions are in each unit cell of NaCl? A)1 Na⁺ ion and 1 Cl^- ion B)2 Na⁺ ions and 2 Cl^- ions C)4 Na⁺ ions and 4 Cl^- ions D)8 Na⁺ ions and 8 Cl^- ions

Question

Quizplus · Accepted Answer

In a cubic unit cell, the corner atoms contribute 1/8th of an atom each to the unit cell, and there are 8 corners, so the total contribution from corners is 1 atom. The face-centered atoms contribute 1/2 an atom each, and there are 6 faces, so the total contribution from faces is 3 atoms. Since Cl^- ions are on each corner and each face, they contribute a total of 4 Cl^- ions per unit cell. Na^+ ions occupy the octahedral voids in the structure, matching the number of Cl^- ions to maintain charge neutrality, resulting in 4 Na^+ ions per unit cell.

NaCl Crystallizes in a Cubic Unit Cell with Cl- Ions

NaCl Crystallizes in a Cubic Unit Cell with Cl^- Ions