Aluminium has a higher atomic packing factor than molybdenum

Aluminium has a higher atomic packing factor than molybdenum by about 6%. This means that:

1. Aluminium is heavier than molybdenum
2. The ratio of the volume of the unit cell to the volume of the atoms per unit cell is lower in aluminium
3. The ratio of the number of atoms per unit cell to size of the cell is roughly equal to both
4. The distance between atoms are equal for both

The atomic packing factor (APF) is the ratio of volume of atoms per unit cell to the volume of the unit cell i.e.

APF	Volume of atoms per unit cell
	Volume of the unit cell

Since aluminium has 6% greater atomic packing factor, then it has a lesser inverse ratio of volume of unit cell to volume of atoms per unit cell.