## Primitive Cubic Unit Cell – Class 12 | Chapter – 1 | Chemistry Short Notes Series PDF for NEET & JEE

Primitive Cubic Unit Cell: The primitive cubic unit cell is one of the simplest types of unit cells and is characterized by a simple cubic lattice with lattice points (or corners) at each corner of the cube. A primitive cubic unit cell contains one lattice point or one atom at each of its corners, and the atoms occupy the same position in each unit cell. Therefore, the number of atoms in a primitive cubic unit cell is equal to one.

## Primitive Cubic Unit Cell

The edge length (a) of a primitive cubic unit cell can be determined using the relationship between the lattice constant (a) and the atomic radius (r) of the atoms in the crystal. In a primitive cubic unit cell, the distance between two adjacent lattice points (or the edge length of the unit cell) is equal to two times the atomic radius. Therefore, the edge length (a) of a primitive cubic unit cell can be expressed as:

a = 2∙r

The coordination number of the atoms in a primitive cubic lattice is equal to six, as each atom is in contact with six neighboring atoms. The packing fraction of a primitive cubic lattice is relatively low, at around 0.52, meaning that there is a significant amount of empty space in the lattice.

## Importance of Primitive Cubic Unit Cell

It is important in the study of crystallography and materials science because it is the simplest and most fundamental type of unit cell. By studying the properties and behavior of materials that have a primitive cubic lattice, scientists can gain a better understanding of more complex crystal structures and their properties.

Some of the key importance are:

• Simplest Crystal Structure: The primitive cubic unit cell is the simplest crystal structure, consisting of a simple cubic lattice with atoms or molecules located at each corner of the cube. It provides a basic and fundamental model for understanding more complex crystal structures.
• Used in Crystallography Studies: The primitive cubic lattice is a useful model for studying crystallography, as it provides a simple and easy-to-understand example of a crystal lattice. By understanding the structure and properties of the primitive cubic lattice, scientists can better understand more complex crystal structures.
• Basic Model for Metals: Many metals, such as iron and copper, have a close-packed crystal structure that is based on the primitive cubic lattice. Understanding the properties of the primitive cubic lattice is therefore essential for understanding the properties of these materials.
• Used in Education: The primitive cubic unit cell is often used in education to teach students about crystal structures and materials science. By understanding the properties of the primitive cubic lattice, students can gain a better understanding of more complex crystal structures and their properties.

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