| Structural type | A2 |
| Common name | body-centered cubic (bcc) |
| Prototype | W |
| Pearson symbol | cI2 |
| Space group | 229 Im-3m Oh9 |
| Chemical formula | A |
| Bonding | metallic |
| Atomic positions | A (2a) 0 0 0 |
| Coordination | 8cb + 6o with r2/r1=2/sqrt(3)≈1.15 |
| PDB files | A2, voids (4t/6by at 12d/6b by H) |
| Substructures | Aa – tetragonal distortion, Ai – rhombohedral distortion |
| Substances | alkali and some other metals (see the table below), many metals before melting |
δ=sqrt(27/32)≈.92 increases at tetragonal distortions and decreases at rhombohedral distortions.
| A | a | |
|---|---|---|
| α-Fe | 2.8665 | T<1180K |
| Cr | 2.8848 | |
| V | 3.0282 | |
| Mo | 3.1474 | |
| W | 3.1652 | |
| Nb | 3.2941 | |
| Ta | 3.3025 | |
| Li | 3.5023 | |
| Na | 4.282 | |
| Eu | 4.572 | |
| Ba | 5.019 | |
| K | 5.247 | |
| Rb | 5.70 | |
| Cs | 6.141 |