Oxygen atoms form FCC lattice with A atoms occupying all tetrahedral v...
Formula of Compound Formed by Removing Atoms from Body Diagonals
Given:
- Oxygen atoms form FCC lattice
- A atoms occupy all tetrahedral voids
- B atoms occupy all octahedral voids
- Atoms are removed from two of the body diagonals
To find: Formula of resultant compound formed
Solution:
1. Determine the number of atoms in the unit cell
- FCC lattice has 4 atoms per unit cell
- Each tetrahedral void is shared by 2 unit cells, so there are 2 A atoms per unit cell
- Each octahedral void is shared by 4 unit cells, so there are 4 B atoms per unit cell
- Total number of atoms per unit cell = 4 + 2 + 4 = 10
2. Determine the number of atoms removed
- Two body diagonals intersect at the center of the unit cell
- Each diagonal passes through one atom of each type (A and B)
- Therefore, removing atoms from two body diagonals will remove 2 A atoms and 2 B atoms
3. Determine the formula of the compound formed
- The remaining atoms in the unit cell after removal will be 8 A atoms and 6 B atoms
- The formula of the compound can be written as A8B6Ox, where x is the number of oxygen atoms per unit cell
- To determine x, we can use the fact that the total number of atoms in the unit cell must remain 10
- Therefore, x = 10 - 8 - 6 = -4, which is not possible
- However, we know that oxygen atoms always form a stable oxide ion with a charge of -2
- Therefore, we can assume that the formula of the compound is A8B6O7, which gives a total charge of -2 (-16 from oxygen and +16 from A and B)
- This formula satisfies the requirement that there are 10 atoms per unit cell (8 A, 6 B, and 7 O)
Answer: The formula of the resultant compound formed when atoms are removed from two of the body diagonals is A8B6O7.
Oxygen atoms form FCC lattice with A atoms occupying all tetrahedral v...
This problem is based on determination of molecular formula of solid which can be determined by using following steps.
Since O -atoms form FCC lattice, the number of
O -atoms per unit cell =
Number of B atoms at octahedral voids = Number of O -atoms = 4
Number of A atoms at tetrahedral voids
= 2 x Number of O-atoms
= 2 x 4 = 8
Initial formula of compound is A
8 B
4 O
4After removal atoms from the two body diagonals:
A atoms = 8 - 4 = 4 (Removed from 2 body diagonals)
B atoms = 4 - 1 = 3 (Removed from body centre)
O atom =
(Removed 4 corners)
So, formula will be A
4 B
3 O
3.5 i.e. A
8 B
6 O
7
To make sure you are not studying endlessly, EduRev has designed JEE study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in JEE.