Editing Cubic crystal system (section)

==Single element structures==
[[File:visualisation_diamond_cubic.svg|thumb|upright|Visualisation of a diamond cubic unit cell: 1. Components of a unit cell, 2. One unit cell, 3. A lattice of 3 x 3 x 3 unit cells]]
{{See also|Periodic table (crystal structure)}}
As a rule, since atoms in a solid attract each other, the more tightly packed arrangements of atoms tend to be more common. (Loosely packed arrangements do occur, though, for example if the [[Orbital hybridisation|orbital hybridization]] demands certain [[Molecular geometry|bond angles]].) Accordingly, the primitive cubic structure, with especially low atomic packing factor, is rare in nature, but is found in [[polonium]].<ref>{{Greenwood&Earnshaw}}</ref><ref>The original discovery was in J. Chem. Phys. '''14''', 569 (1946).</ref> The ''bcc'' and ''fcc'', with their higher densities, are both quite common in nature. Examples of ''bcc'' include [[iron]], [[chromium]], [[tungsten]], and [[niobium]]. Examples of ''fcc'' include [[aluminium]], [[copper]], [[gold]] and [[silver]].

Another important cubic crystal structure is the [[diamond cubic]] structure, which can appear in [[carbon]], [[silicon]], [[germanium]], and [[tin]]. Unlike fcc and bcc, this structure is not a lattice, since it contains multiple atoms in its [[primitive cell]]. Other cubic elemental structures include the [[A15 phases|A15 structure]] found in [[tungsten]], and the extremely complicated structure of [[manganese]].