Why it is impossible to pack atoms, molecules and ions without any empty space between them?a)Constituent particles are assumed to be rectangular.b)Constituent particles are assumed to be spheres.c)Constituent particles are assumed to be squares.d)Constituent particles are assumed to be hexagonal.Correct answer is option 'B'. Can you explain this answer?

Question

Accepted Answer

Close packing in crystals refers to space efficient arrangement of constituent particles in a crystal lattice. To understand this packing more clearly we have to assume all particles (atoms, molecules and ions) are of the same spherical solid shape.

So the unit cell of a lattice is a cubic shape. Now when we stack spheres in the cell, there will always be some empty spaces. To minimize these empty spaces, the arrangement of these spheres must be very efficient. The spheres should be arranged as close together as possible to eliminate empty spaces.

Answer

In close packing of solids, the constituent particles, i.e. the atoms, molecules and ions are assumed to be spheres.

Answer

Why it is impossible to pack atoms, molecules, and ions without any empty space between them?

Atoms, molecules, and ions are the building blocks of matter. They have a certain shape and size, which affects how they can be packed together. When these particles are packed, it is impossible to eliminate all empty space between them due to their inherent characteristics.

Assumption of Spherical Particles

In this context, the assumption that constituent particles are spheres is crucial in understanding why empty space is inevitable. The spherical shape is a reasonable approximation for most atoms, molecules, and ions.

Reason 1: Particle Size and Shape

The size and shape of the particles play a significant role in determining the arrangement and the presence of empty spaces. When spherical particles are packed together, the only way to fill the space is by arranging them in a specific pattern, which results in the appearance of voids between the particles.

Reason 2: Closest Packing

When considering the closest possible packing of spheres, which is the most efficient arrangement, there are two main possibilities:
- Hexagonal Closest Packing (hcp): In this arrangement, the spheres are stacked in a hexagonal pattern, with each subsequent layer positioned in the depressions of the previous layer. Even in this arrangement, there are small, triangular-shaped voids between the spheres.
- Face-Centered Cubic (fcc): Another efficient packing arrangement involves stacking the spheres in a cubic pattern, with an additional sphere placed in the center of each face of the cube formed by the first layer. This arrangement also results in empty spaces between the spheres.

Conclusion

Regardless of the specific arrangement, the assumption that constituent particles are spheres leads to the presence of empty space between them. Even in the most efficient packing arrangements, such as hexagonal closest packing or face-centered cubic, voids or empty spaces are unavoidable. Therefore, it is impossible to pack atoms, molecules, and ions without any empty space between them.

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