Unit Cells and Crystal Symmetries

The video tutorial explains the concept of unit cells in crystal structures, highlighting the differences between primitive and non-primitive unit cells. It discusses how unit cells are defined by lattice points and how they form crystal structures. The video also provides examples of body-centered cubic (BCC) and face-centered cubic (FCC) unit cells, explaining their atomic contributions. Finally, it introduces the concept of symmetries in unit cells and the Bravais lattice, setting the stage for further exploration in subsequent videos.

What is the fundamental unit of a crystal system?

• Crystal Lattice

• Unit Cell

• Atom

• Molecule

How is a unit cell defined in terms of lattice points?

• By the arrangement of molecules

• By the number of atoms

• By the shape of the crystal

• By imaginary points describing atom arrangement

What is the contribution of an atom located at the face of a unit cell?

• 1/2

• 1/4

• 1/8

• 1

In a simple cubic cell, what is the total contribution of atoms in the unit cell?

• 4

• 3

• 2

• 1

Which type of unit cell has a total atom contribution greater than 1?

• Hexagonal

• Primitive

• Non-primitive

• Simple cubic

What is the total contribution of atoms in a BCC unit cell?

• 1

• 4

• 2

• 3

Which of the following is a non-primitive unit cell?

• Hexagonal

• Tetragonal

• Body-centered cubic

• Simple cubic

How many types of symmetries are found in unit cells?

• 5

• 2

• 4

• 3

Which symmetry is not found in unit cells?

• Shear

• Reflection

• Rotational

• Translational

What is the name given to unit cells that exist according to symmetries?

• Atomic lattice

• Crystal lattice

• Bravais lattice

• Molecular lattice