Some of the properties of crystalline solids depend on the crystal structure of the material and how atoms, ions, or molecules are spatially arranged. A crystal lattice is a repeating pattern of mathematical points that extends throughout space. This repetition is caused by the forces of chemical bonding. This repeated pattern controls properties like strength, ductility, density, conductivity (property of conducting or transmitting heat, electricity, etc.), and shape. There are 14 general types of such patterns known as Bravais lattices. Three relatively simple crystal structures are found for most of the common metals.
In a body-centered cubic (bcc) arrangement of atoms, the unit cell consists of eight atoms at the corners of a cube and one atom at the body center of the cube. In a bcc arrangement, a unit cell contains (8 corner atoms × ⅛) + (1 center atom × 1) = 2 atoms. The packing is more efficient (68%) than simple cubic, and the structure is common for alkali and early transition metals. Metals containing BCC structures include ferrite, chromium, vanadium, molybdenum, and tungsten. These metals possess high strength and low ductility.