Simple cubic

Definition

Simple cubic refers to a type of crystal structure where atoms are arranged at the corners of a cube. In this structure, each corner atom is shared among eight adjacent cubes, which leads to a unit cell that contains one complete atom per unit cell. This arrangement is one of the most basic forms of atomic packing and serves as a foundation for understanding more complex crystal structures.

5 Must Know Facts For Your Next Test

1. In a simple cubic structure, the coordination number is 6, meaning each atom is in contact with six other atoms.
2. The atomic packing efficiency in a simple cubic structure is about 52%, which is relatively low compared to other structures like BCC and FCC.
3. The simple cubic lattice is found in a few metallic elements, such as polonium and lithium, though it is not common among metals.
4. The length of the cube edge can be related to atomic radius through the formula: edge length = 2 * atomic radius.
5. Simple cubic structures can be described using Miller indices, which provide a shorthand notation for the orientations of the crystal planes.

Review Questions

• How does the simple cubic structure compare to other types of cubic structures in terms of atomic arrangement and packing efficiency?
  • The simple cubic structure features atoms located only at the corners of the cube, while body-centered cubic (BCC) has an additional atom at the center, and face-centered cubic (FCC) has atoms at both face centers and corners. This difference in atomic arrangement affects packing efficiency; simple cubic has about 52% packing efficiency, whereas BCC is around 68% and FCC is about 74%. Thus, FCC is the most efficient, maximizing space utilization compared to simple cubic.
• Explain how the coordination number in a simple cubic structure influences its physical properties compared to structures with higher coordination numbers.
  • In a simple cubic structure, the coordination number is 6, meaning each atom touches six others. This lower coordination can lead to weaker metallic bonding compared to structures with higher coordination numbers like BCC and FCC, which have coordination numbers of 8 and 12, respectively. The stronger bonding in higher coordination structures often results in improved mechanical properties such as hardness and ductility.
• Evaluate the significance of understanding simple cubic structures in relation to materials science and engineering applications.
  • Understanding simple cubic structures is crucial because they represent one of the fundamental building blocks in materials science. Knowledge of these structures helps in predicting material properties, such as conductivity and strength. This foundational understanding allows engineers to design new materials with desired characteristics by modifying crystal structures or exploring alloys that may have simple cubic arrangements. Such insights are key for developing innovative materials for various technological applications.

Related terms

Body-centered cubic (BCC): A type of crystal structure where one atom is located at the center of the cube in addition to the atoms at each corner, resulting in two atoms per unit cell.

Face-centered cubic (FCC): A crystal structure where atoms are located at each corner and the centers of all the cube faces, leading to four atoms per unit cell.

Lattice parameters: The dimensions and angles that define the size and shape of the unit cell in a crystal lattice.