How do you determine the number of atoms in each unit cell?

Answer 1

Count the number of atoms that are all the way inside the cell. Each of these counts as 1. Count the number of atoms that are on a face, but not a corner or edge of the cell. Each of these count as 1/2. Count the number of atoms that are on an edge, but not a corner of the cell. Each of these count as 1/4. Count the number of atoms that are on a corner of the cell. Each of these count as 1/8. The final formula is: inside + 1/2 face + 1/4 edge +1/8 corner = total atoms per cell.

Answer 2

To determine the number of atoms in a unit cell, you need to know the type of unit cell (simple cubic, body-centered cubic, or face-centered cubic) and the atom arrangement within the unit cell. For example, in a simple cubic unit cell, there is one atom at each corner. In a body-centered cubic unit cell, there are atoms at each corner and one in the center. In a face-centered cubic unit cell, there are atoms at each corner and one on each face. Counting these positions allows you to determine the total number of atoms in the unit cell.