Periodic table (crystal structure)
Updated: 12/11/2025, 9:47:40 AM Wikipedia source
This articles gives the crystalline structures of the elements of the periodic table which have been produced in bulk at STP and at their melting point (while still solid) and predictions of the crystalline structures of the rest of the elements.
Tables
· Structure types
α-Pu
α-Pu
Prototype
α-Pu
Strukturbericht
(none)
Diagram
Lattice system
Monoclinic
Space group
P21/m(No. 11)
Atoms per unit cell
16
notes
slightly distorted hexagonal structure. Lattice parameters: a = 618.3 pm, b = 482.2 pm, c = 1096.3 pm, β = 101.79°
β-S
β-S
Prototype
β-S
Strukturbericht
(none)
Lattice system
Monoclinic
Space group
P21/c(No. 14)
Atoms per unit cell
32
α-Np
α-Np
Prototype
α-Np
Strukturbericht
Ac
Lattice system
Orthorhombic
Space group
Pnma(No. 62)
Atoms per unit cell
8
notes
highly distorted bcc structure. Lattice parameters: a = 666.3 pm, b = 472.3 pm, c = 488.7 pm
α-U
α-U
Prototype
α-U
Strukturbericht
A20
Diagram
Lattice system
Orthorhombic
Space group
Cmcm(No. 63)
Atoms per unit cell
4
Coordination
Each atom has four near neighbours, 2 at 275.4 pm, 2 at 285.4 pm. The next four at distances 326.3 pm and four more at 334.2 pm.
notes
Strongly distorted hcp structure.
α-Ga
α-Ga
Prototype
α-Ga
Strukturbericht
A11
Diagram
Lattice system
Orthorhombic
Space group
Cmce(No. 64)
Atoms per unit cell
8
Coordination
each Ga atom has one nearest neighbour at 244 pm, 2 at 270 pm, 2 at 273 pm, 2 at 279 pm.
notes
The structure is related to that of iodine.
b-P
b-P
Prototype
b-P
Strukturbericht
A17
Diagram
Lattice system
Orthorhombic
Space group
Cmce(No. 64)
Atoms per unit cell
8
notes
Specifically the black phosphorus form of phosphorus.
Cl
Cl
Prototype
Cl
Strukturbericht
A14
Diagram
Lattice system
Orthorhombic
Space group
Cmce(No. 64)
Atoms per unit cell
8
α-S
α-S
Prototype
α-S
Strukturbericht
A16
Lattice system
Orthorhombic
Space group
Fddd(No. 70)
Atoms per unit cell
16
In
In
Prototype
In
Strukturbericht
A6
Diagram
Lattice system
Tetragonal
Space group
I4/mmm(No. 139)
Atoms per unit cell
2
notes
Identical symmetry to the α-Pa type structure. Can be considered slightly distorted from an ideal Cu type face-centered cubic structure which has
c
/
a
=
2
{\displaystyle c/a={\sqrt {2}}}
.
α-Pa
α-Pa
Prototype
α-Pa
Strukturbericht
Aa
Lattice system
Tetragonal
Space group
I4/mmm(No. 139)
Atoms per unit cell
2
notes
Identical symmetry to the In type structure. Can be considered slightly distorted from an ideal W type body centered cubic structure which has
c
/
a
=
1
{\displaystyle c/a=1}
.
β-Sn
β-Sn
Prototype
β-Sn
Strukturbericht
A5
Lattice system
Tetragonal
Space group
I41/amd(No. 141)
Atoms per unit cell
4
Coordination
4 neighbours at 302 pm; 2 at 318 pm; 4 at 377 pm; 8 at 441 pm
notes
white tin form (thermodynamical stable above 286.4 K)
β-B
β-B
Prototype
β-B
Strukturbericht
(none)
Diagram
Lattice system
Rhombohedral
Space group
R3m(No. 166)
Atoms per unit cell
105 (rh.) 315 (hex.)
notes
Partly due to its complexity, whether this structure is the ground state of Boron has not been fully settled.
α-As
α-As
Prototype
α-As
Strukturbericht
A7
Diagram
Lattice system
Rhombohedral
Space group
R3m(No. 166)
Atoms per unit cell
2 (rh.)6 (hex.)
Coordination
in grey metallic form, each As atom has 3 neighbours in the same sheet at 251.7pm; 3 in adjacent sheet at 312.0 pm. each Bi atom has 3 neighbours in the same sheet at 307.2 pm; 3 in adjacent sheet at 352.9 pm. each Sb atom has 3 neighbours in the same sheet at 290.8pm; 3 in adjacent sheet at 335.5 pm.
notes
puckered sheet
α-Sm
α-Sm
Prototype
α-Sm
Strukturbericht
(none)
Diagram
Lattice system
Rhombohedral
Space group
R3m(No. 166)
Atoms per unit cell
3 (rh.)9 (hex.)
Coordination
12 nearest neighbours
notes
complex hcp with 9-layer repeat: ABCBCACAB....
α-Hg
α-Hg
Prototype
α-Hg
Strukturbericht
A10
Diagram
Lattice system
Rhombohedral
Space group
R3m(No. 166)
Atoms per unit cell
1 (rh.)3 (hex.)
Coordination
6 nearest neighbours at 234 K and 1 atm (it is liquid at room temperature and thus has no crystal structure at ambient conditions!)
notes
Identical symmetry to the β-Po structure, distinguished based on details about the basis vectors of its unit cell. This structure can also be considered to be a distorted hcp lattice with the nearest neighbours in the same plane being approx 16% farther away
β-Po
β-Po
Prototype
β-Po
Strukturbericht
Ai
Lattice system
Rhombohedral
Space group
R3m(No. 166)
Atoms per unit cell
1 (rh.)3 (hex.)
notes
Identical symmetry to the α-Hg structure, distinguished based on details about the basis vectors of its unit cell.
γ-Se
γ-Se
Prototype
γ-Se
Strukturbericht
A8
Diagram
Lattice system
Hexagonal
Space group
P321(No. 154)
Atoms per unit cell
3
Mg
Mg
Prototype
Mg
Strukturbericht
A3
Diagram
Lattice system
Hexagonal
Space group
P63/mmc(No. 194)
Atoms per unit cell
2
Coordination
Zn has 6 nearest neighbors in same plane: 6 in adjacent planes 14% farther away Cd has 6 nearest neighbours in the same plane- 6 in adjacent planes 15% farther away
notes
If the unit cell axial ratio is exactly
2
2
3
≈
1.633
{\textstyle 2{\sqrt {\frac {2}{3}}}\approx 1.633}
the structure would be a mathematical hexagonal close packed (HCP) structure. However, in real materials there are deviations from this in some metals where the unit cell is distorted in one direction but the structure still retains the hcp space group—remarkable all the elements have a ratio of lattice parameters c/a < 1.633 (best are Mg and Co and worst Be with c/a ~ 1.568). In others like Zn and Cd the deviations from the ideal change the symmetry of the structure and these have a lattice parameter ratio c/a > 1.85.
g-C
g-C
Prototype
g-C
Strukturbericht
A9
Diagram
Lattice system
Hexagonal
Space group
P63/mmc(No. 194)
Atoms per unit cell
4
notes
Specifically the graphite form of carbon.
α-La
α-La
Prototype
α-La
Strukturbericht
A3'
Diagram
Lattice system
Hexagonal
Space group
P63/mmc(No. 194)
Atoms per unit cell
4
notes
The Double hexagonal close packed (DHCP) structure. Similar to the ideal hcp structure, the perfect dhcp structure should have a lattice parameter ratio of
c
a
=
4
2
3
≈
3.267.
{\textstyle {\frac {c}{a}}=4{\sqrt {\frac {2}{3}}}\approx 3.267.}
In the real dhcp structures of 5 lanthanides (including β-Ce)
c
/
2
a
{\textstyle c/2a}
variates between 1.596 (Pm) and 1.6128 (Nd). For the four known actinides dhcp lattices the corresponding number vary between 1.620 (Bk) and 1.625 (Cf).
β-N
β-N
Prototype
β-N
Strukturbericht
(none)
Lattice system
Hexagonal
Space group
P63/mmc(No. 194)
Atoms per unit cell
4
α-Po
α-Po
Prototype
α-Po
Strukturbericht
Ah
Diagram
Lattice system
Cubic
Space group
Pm3m(No. 221)
Atoms per unit cell
1
Coordination
6 nearest neighbours
notes
simple cubic lattice. The atoms in the unit cell are at the corner of a cube.
γ-O
γ-O
Prototype
γ-O
Strukturbericht
(none)
Diagram
Lattice system
Cubic
Space group
Pm3n(No. 223)
Atoms per unit cell
16
notes
Closely related to the β-W structure, except with a diatomic oxygen molecule in place of each tungsten atom. The molecules can rotate in place, but the direction of rotation for some of the molecules is restricted.
α-Mn
α-Mn
Prototype
α-Mn
Strukturbericht
A12
Diagram
Lattice system
Cubic
Space group
I43m(No. 217)
Atoms per unit cell
58
Coordination
Unit cell contains Mn atoms in 4 different environments.
notes
Distorted bcc
W
W
Prototype
W
Strukturbericht
A2
Diagram
Lattice system
Cubic
Space group
Im3m(No. 229)
Atoms per unit cell
2
notes
The Body centered cubic structure (BCC). It is not a close packed structure. In this each metal atom is at the centre of a cube with 8 nearest neighbors, however the 6 atoms at the centres of the adjacent cubes are only approximately 15% further away so the coordination number can therefore be considered to be 14 when these are on one 4 fold axe structure becomes face-centred cubic (cubic close packed).
Cu
Cu
Prototype
Cu
Strukturbericht
A1
Diagram
Lattice system
Cubic
Space group
Fm3m(No. 225)
Atoms per unit cell
4
notes
The face-centered cubic (cubic close packed) structure. More content relating to number of planes within structure and implications for glide/slide e.g. ductility.
d-C
d-C
Prototype
d-C
Strukturbericht
A4
Diagram
Lattice system
Cubic
Space group
Fd3m(No. 227)
Atoms per unit cell
8
notes
The diamond cubic (DC) structure. Specifically the diamond form of Carbon.
| Prototype | Strukturbericht | Diagram | Lattice system | Space group | Atoms per unit cell | Coordination | notes |
| α-Pu | (none) | | Monoclinic | P21/m(No. 11) | 16 | slightly distorted hexagonal structure. Lattice parameters: a = 618.3 pm, b = 482.2 pm, c = 1096.3 pm, β = 101.79° | |
| β-S | (none) | Monoclinic | P21/c(No. 14) | 32 | |||
| α-Np | Ac | Orthorhombic | Pnma(No. 62) | 8 | highly distorted bcc structure. Lattice parameters: a = 666.3 pm, b = 472.3 pm, c = 488.7 pm | ||
| α-U | A20 | | Orthorhombic | Cmcm(No. 63) | 4 | Each atom has four near neighbours, 2 at 275.4 pm, 2 at 285.4 pm. The next four at distances 326.3 pm and four more at 334.2 pm. | Strongly distorted hcp structure. |
| α-Ga | A11 | | Orthorhombic | Cmce(No. 64) | 8 | each Ga atom has one nearest neighbour at 244 pm, 2 at 270 pm, 2 at 273 pm, 2 at 279 pm. | The structure is related to that of iodine. |
| b-P | A17 | | Orthorhombic | Cmce(No. 64) | 8 | Specifically the black phosphorus form of phosphorus. | |
| Cl | A14 | | Orthorhombic | Cmce(No. 64) | 8 | ||
| α-S | A16 | Orthorhombic | Fddd(No. 70) | 16 | |||
| In | A6 | | Tetragonal | I4/mmm(No. 139) | 2 | Identical symmetry to the α-Pa type structure. Can be considered slightly distorted from an ideal Cu type face-centered cubic structure which has c / a = 2 {\displaystyle c/a={\sqrt {2}}} . | |
| α-Pa | Aa | Tetragonal | I4/mmm(No. 139) | 2 | Identical symmetry to the In type structure. Can be considered slightly distorted from an ideal W type body centered cubic structure which has c / a = 1 {\displaystyle c/a=1} . | ||
| β-Sn | A5 | Tetragonal | I41/amd(No. 141) | 4 | 4 neighbours at 302 pm; 2 at 318 pm; 4 at 377 pm; 8 at 441 pm | white tin form (thermodynamical stable above 286.4 K) | |
| β-B | (none) | | Rhombohedral | R3m(No. 166) | 105 (rh.) 315 (hex.) | Partly due to its complexity, whether this structure is the ground state of Boron has not been fully settled. | |
| α-As | A7 | | Rhombohedral | R3m(No. 166) | 2 (rh.)6 (hex.) | in grey metallic form, each As atom has 3 neighbours in the same sheet at 251.7pm; 3 in adjacent sheet at 312.0 pm. each Bi atom has 3 neighbours in the same sheet at 307.2 pm; 3 in adjacent sheet at 352.9 pm. each Sb atom has 3 neighbours in the same sheet at 290.8pm; 3 in adjacent sheet at 335.5 pm. | puckered sheet |
| α-Sm | (none) | | Rhombohedral | R3m(No. 166) | 3 (rh.)9 (hex.) | 12 nearest neighbours | complex hcp with 9-layer repeat: ABCBCACAB.... |
| α-Hg | A10 | | Rhombohedral | R3m(No. 166) | 1 (rh.)3 (hex.) | 6 nearest neighbours at 234 K and 1 atm (it is liquid at room temperature and thus has no crystal structure at ambient conditions!) | Identical symmetry to the β-Po structure, distinguished based on details about the basis vectors of its unit cell. This structure can also be considered to be a distorted hcp lattice with the nearest neighbours in the same plane being approx 16% farther away |
| β-Po | Ai | Rhombohedral | R3m(No. 166) | 1 (rh.)3 (hex.) | Identical symmetry to the α-Hg structure, distinguished based on details about the basis vectors of its unit cell. | ||
| γ-Se | A8 | | Hexagonal | P321(No. 154) | 3 | ||
| Mg | A3 | | Hexagonal | P63/mmc(No. 194) | 2 | Zn has 6 nearest neighbors in same plane: 6 in adjacent planes 14% farther away Cd has 6 nearest neighbours in the same plane- 6 in adjacent planes 15% farther away | If the unit cell axial ratio is exactly 2 2 3 ≈ 1.633 {\textstyle 2{\sqrt {\frac {2}{3}}}\approx 1.633} the structure would be a mathematical hexagonal close packed (HCP) structure. However, in real materials there are deviations from this in some metals where the unit cell is distorted in one direction but the structure still retains the hcp space group—remarkable all the elements have a ratio of lattice parameters c/a < 1.633 (best are Mg and Co and worst Be with c/a ~ 1.568). In others like Zn and Cd the deviations from the ideal change the symmetry of the structure and these have a lattice parameter ratio c/a > 1.85. |
| g-C | A9 | | Hexagonal | P63/mmc(No. 194) | 4 | Specifically the graphite form of carbon. | |
| α-La | A3' | | Hexagonal | P63/mmc(No. 194) | 4 | The Double hexagonal close packed (DHCP) structure. Similar to the ideal hcp structure, the perfect dhcp structure should have a lattice parameter ratio of c a = 4 2 3 ≈ 3.267. {\textstyle {\frac {c}{a}}=4{\sqrt {\frac {2}{3}}}\approx 3.267.} In the real dhcp structures of 5 lanthanides (including β-Ce) c / 2 variates between 1.596 (Pm) and 1.6128 (Nd). For the four known actinides dhcp lattices the corresponding number vary between 1.620 (Bk) and 1.625 (Cf). | |
| β-N | (none) | Hexagonal | P63/mmc(No. 194) | 4 | |||
| α-Po | Ah | | Cubic | Pm3m(No. 221) | 1 | 6 nearest neighbours | simple cubic lattice. The atoms in the unit cell are at the corner of a cube. |
| γ-O | (none) | | Cubic | Pm3n(No. 223) | 16 | Closely related to the β-W structure, except with a diatomic oxygen molecule in place of each tungsten atom. The molecules can rotate in place, but the direction of rotation for some of the molecules is restricted. | |
| α-Mn | A12 | | Cubic | I43m(No. 217) | 58 | Unit cell contains Mn atoms in 4 different environments. | Distorted bcc |
| W | A2 | | Cubic | Im3m(No. 229) | 2 | The Body centered cubic structure (BCC). It is not a close packed structure. In this each metal atom is at the centre of a cube with 8 nearest neighbors, however the 6 atoms at the centres of the adjacent cubes are only approximately 15% further away so the coordination number can therefore be considered to be 14 when these are on one 4 fold axe structure becomes face-centred cubic (cubic close packed). | |
| Cu | A1 | | Cubic | Fm3m(No. 225) | 4 | The face-centered cubic (cubic close packed) structure. More content relating to number of planes within structure and implications for glide/slide e.g. ductility. | |
| d-C | A4 | | Cubic | Fd3m(No. 227) | 8 | The diamond cubic (DC) structure. Specifically the diamond form of Carbon. |
References
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- J. Chem. Soc. Trans.https://zenodo.org/record/1529110
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