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

Body Centred Cubic Unit Cell: The body-centered cubic (BCC) unit cell is a type of unit cell that is characterized by a simple cubic lattice with an additional atom located at the center of the cube. A body-centered cubic unit cell contains one lattice point or one atom at each of its corners, and an additional atom at the center of the cube. Therefore, the number of atoms in a body-centered cubic unit cell is equal to two

## Body Centred Cubic Unit Cell

The edge length (a) of a body centred 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 body-centered cubic unit cell, the distance between two adjacent lattice points (or the edge length of the unit cell) is equal to 4√3 times the atomic radius. Therefore, the edge length (a) of a body-centered cubic unit cell can be expressed as:

a = 4√3∙r

The coordination number of the atoms in a body-centered cubic lattice is equal to eight, as each atom is in contact with eight neighboring atoms. The packing fraction of a body-centered cubic lattice is relatively high, at around 0.68, meaning that there is relatively little empty space in the lattice.

## Properties of Body Centred Cubic Unit Cell

Some of the key properties of the body centred cubic unit cell are:

• Coordination Number: The coordination number of the atoms in a BCC lattice is eight, as each atom is in contact with eight neighboring atoms. This results in a more closely packed structure compared to the primitive cubic lattice, which has a coordination number of six.
• Packing Fraction: The packing fraction of a BCC lattice is relatively high, at around 0.68. This means that there is relatively little empty space in the lattice, and the atoms are more closely packed together than in a primitive cubic lattice.
• Density: The BCC lattice has a higher density compared to the primitive cubic lattice, as there are more atoms per unit cell. This makes it a useful structure for materials that require high density, such as metals.
• Mechanical Properties: Materials that have a BCC structure tend to have high ductility and toughness, making them useful in applications where strength and toughness are important. BCC metals also tend to be good conductors of electricity and heat.
• Magnetic Properties: Some materials that have a BCC structure, such as iron, exhibit ferromagnetism, where the atoms have a net magnetic moment. This makes them useful in applications such as magnetic storage media.

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