For elements that are solid at standard temperature and pressure the table gives the crystalline structure of the most thermodynamically stable form(s) in those conditions. In all other cases the structure given is for the element at its melting point (H, He, N, O, F, Ne, Cl, Ar, Kr, Xe, and Rn are gases at STP; Br, Hg, and probably Cn and Fl are liquids at STP). Predictions are given for At (85), Fr (87), elements 100–113 and 118, which have not been produced in bulk. The latest predictions for Fl (114) could not distinguish between face-centred cubic and hexagonal close-packed structures, which were predicted to be close in energy.^[1] No predictions are available for elements 115–117.

Template:Periodic table (by crystal structure)

Prototype	Crystal system	Space group	coordination number	notes
Cu	cubic	Fm3m		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.
W	cubic	Im3m		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).
La	hexagonal	P63/mmc		The Double hexagonal close packed (DHCP) structure. Similar to the ideal hcp structure, the perfect dhcp structure should have a lattice parameter ratio of ${\textstyle {\frac {c}{a))=4{\sqrt {\frac {2}{3))}\approx 3.267.}$ In the real dhcp structures of 5 lanthanides (including β-Ce) ${\textstyle c/2a}$ 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).[2]
Mn	cubic	I43m	distorted bcc – unit cell contains Mn atoms in 4 different environments.[3]
Mg	hexagonal	P63/mmc	Zn is distorted from ideal hcp. 6 nearest neighbors in same plane: 6 in adjacent planes 14% farther away[3] Cd distorted from ideal hcp. 6 nearest neighbours in the same plane- 6 in adjacent planes 15% farther away[3]	The Hexagonal close packed (HCP) structure. In the ideal hcp structure the unit cell axial ratio is ${\textstyle 2{\sqrt {\frac {2}{3))}\approx 1.633}$. However, 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.
Ga	orthorhombic	Cmca	each Ga atom has one nearest neighbour at 244 pm, 2 at 270 pm, 2 at 273 pm, 2 at 279 pm.[3]	The structure is related to that of iodine.
As	trigonal	R3m	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.[3] each Bi atom has 3 neighbours in the same sheet at 307.2 pm; 3 in adjacent sheet at 352.9 pm.[3] each Sb atom has 3 neighbours in the same sheet at 290.8pm; 3 in adjacent sheet at 335.5 pm.[3]	puckered sheet
In	tetragonal	I4/mmm	slightly distorted fcc structure[3]
Sn	tetragonal	I41/amd	4 neighbours at 302 pm; 2 at 318 pm; 4 at 377 pm; 8 at 441 pm [3]	white tin form (thermodynamical stable above 286.4 K)
Sm	trigonal	R3m	12 nearest neighbours	complex hcp with 9-layer repeat: ABCBCACAB....[4]
Hg	trigonal	R3m	6 nearest neighbours at 234 K and 1 atm (it is liquid at room temperature and thus has no crystal structure at ambient conditions!)	this structure can be considered to be a distorted hcp lattice with the nearest neighbours in the same plane being approx 16% farther away [3]
Po	cubic	Pm3m	6 nearest neighbours	simple cubic lattice. The atoms in the unit cell are at the corner of a cube.
Pa	tetragonal	I4/mmm	body centred tetragonal unit cell, which can be considered to be a distorted bcc
U	orthorhombic	Cmcm	strongly distorted hcp structure. 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.[5]
Np	orthorhombic	Pnma	highly distorted bcc structure. Lattice parameters: a = 666.3 pm, b = 472.3 pm, c = 488.7 pm [6][7]
Pu	monoclinic	P21/m	slightly distorted hexagonal structure. 16 atoms per unit cell. Lattice parameters: a = 618.3 pm, b = 482.2 pm, c = 1096.3 pm, β = 101.79° [8][9]

Many metals adopt close packed structures i.e. hexagonal close packed and face-centred cubic structures (cubic close packed). A simple model for both of these is to assume that the metal atoms are spherical and are packed together in the most efficient way (close packing or closest packing). In closest packing every atom has 12 equidistant nearest neighbours, and therefore a coordination number of 12. If the close packed structures are considered as being built of layers of spheres then the difference between hexagonal close packing and face-centred cubic is how each layer is positioned relative to others. Whilst there are many ways that can be envisaged for a regular buildup of layers:

• hexagonal close packing has alternate layers positioned directly above/below each other: A,B,A,B,... (also termed P6₃/mmc, Pearson symbol hP2, strukturbericht A3) .
• face-centered cubic has every third layer directly above/below each other: A,B,C,A,B,C,... (also termed cubic close packing, Fm3m, Pearson symbol cF4, strukturbericht A1) .
• double hexagonal close packing has layers directly above/below each other, A,B,A,C,A,B,A,C,.... of period length 4 like an alternative mixture of fcc and hcp packing (also termed P6₃/mmc, Pearson Symbol hP4, strukturbericht A3' ).^[10]
• α-Sm packing has a period of 9 layers A,B,A,B,C,B,C,A,C,.... (R3m, Pearson Symbol hR3, strukturbericht C19).^[11]

• Crystal structure

General

• P.A. Sterne; A. Gonis; A.A. Borovoi, eds. (July 1996). "Actinides and the Environment". Proc. of the NATO Advanced Study Institute on Actinides and the Environment. NATO ASI Series. Maleme, Crete, Greece: Kluver Academic Publishers. pp. 59–61. ISBN 0-7923-4968-7.
• L.R. Morss; Norman M. Edelstein; Jean Fuger, eds. (2007). The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Springer. ISBN 978-1402035555.

• Strukturbericht Type A – structure reports for the pure elements
• Crystal Structures for the solid chemical elements at 1 bar