Which term refers to the general class of crystals categorized by symmetry and internal arrangement?

Which term refers to the general class of crystals categorized by symmetry and internal arrangement?

• A. Crystal planes
• B. Crystal systems
• C. Crystalline
• D. Crystal shape (form)

Answer: (B)

Crystals are categorized by how their atoms are arranged in three-dimensional space and how symmetric that arrangement is, which is captured by crystal systems. This term best describes the general class of crystals based on lattice symmetry and unit-cell geometry, grouping minerals into seven systems (cubic, tetragonal, orthorhombic, hexagonal, trigonal, monoclinic, triclinic) to reflect their internal arrangement. Crystal planes are specific flat faces defined by Miller indices, not a broad classification of the lattice. Crystal shape (form) refers to the external appearance of the crystal, not its internal symmetry. Crystalline is an adjective describing a material with a regularly ordered lattice, not the category itself. So crystal systems is the most appropriate term.

Crystals are categorized by how their atoms are arranged in three-dimensional space and how symmetric that arrangement is, which is captured by crystal systems. This term best describes the general class of crystals based on lattice symmetry and unit-cell geometry, grouping minerals into seven systems (cubic, tetragonal, orthorhombic, hexagonal, trigonal, monoclinic, triclinic) to reflect their internal arrangement. Crystal planes are specific flat faces defined by Miller indices, not a broad classification of the lattice. Crystal shape (form) refers to the external appearance of the crystal, not its internal symmetry. Crystalline is an adjective describing a material with a regularly ordered lattice, not the category itself. So crystal systems is the most appropriate term.