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.

Standard temperature and pressure The following table gives the crystalline structure of the most thermodynamically stable form(s) for elements that are solid at standard temperature and pressure. Each element is shaded by a color representing its respective Bravais lattice, except that all orthorhombic lattices are grouped together. Crystal structure of elements in the periodic table at standard temperature and pressure1H 2He 3 Li W4 Be Mg5 Bβ-B6 Cg-C7 N 8 O 9 F 10 Ne 11 Na W12 Mg Mg13 Al Cu14 Si d-C15 P b-P16 S α-S17 Cl  18 Ar  19KW20 Ca Cu21Sc Mg22Ti Mg23 V W24Cr W25 Mnα-Mn26Fe W27 Co Mg28 Ni Cu29Cu Cu30 Zn Mg31Ga α-Ga32 Ge d-C33As α-As34Se γ-Se35Br  36 Kr  37 Rb W38 Sr Cu39 Y Mg40Zr Mg41Nb W42 Mo W43 Tc Mg44 Ru Mg45 Rh Cu46 Pd Cu47 Ag Cu48 Cd Mg49 In In50 Sn β-Sn51 Sb α-As52Te γ-Se53I Cl54 Xe  55 Cs W56 Ba W 71Lu Mg72 Hf Mg73 Ta W74 W W75 Re Mg76 Os Mg77 IrCu78 Pt Cu79 Au Cu80 Hg  81 Tl Mg82 Pb Cu83 Bi α-As84 Po α-Po85 At  86 Rn  87Fr 88 RaW 103Lr 104 Rf 105 Db 106 Sg 107 Bh 108 Hs 109 Mt 110 Ds 111 Rg 112 Cn 113 Nh 114 Fl 115 Mc 116 Lv 117 Ts 118 Og  colspan="3" 57La α-La 58Ceα-La 59Pr α-La 60Nd α-La 61Pm α-La 62Smα-Sm 63EuW 64Gd Mg 65Tb Mg 66Dy Mg 67Ho Mg 68Er Mg 69Tm Mg 70YbCu colspan="3" 89Ac Cu 90ThCu 91Paα-Pa 92Uα-U 93Npα-Np 94Puα-Pu 95Am α-La 96Cm α-La 97Bk α-La 98Cf α-La 99Es Cu100Fm 101Md 102No  Legend:

Melting point and standard pressure The following table gives the most stable crystalline structure of each element at its melting point at atmospheric pressure (H, He, N, O, F, Ne, Cl, Ar, Kr, Xe, and Rn are gases at STP; Br and Hg are liquids at STP.) Note that helium does not have a melting point at atmospheric pressure, but it adopts a magnesium-type hexagonal close-packed structure under high pressure.

Crystal structures of elements at their melting points at atmospheric pressure1H13 KMg2He*3 Li453 KW4 Be1560 KW5 B2349 Kβ-B6 C3800 Kg-C7 N63 Kβ-N8 O 54 Kγ-O9 F53 Kγ-O10 Ne24 KCu11 Na370 KW12 Mg923 KMg13 Al 933 KCu14 Si 1687 Kd-C15 P 883 Kb-P16 S 393 Kβ-S17 Cl 171 KCl18 Ar 83 KCu19K336 KW20 Ca 1115 KW21Sc1814 KW22Ti 1941 KW23 V2183 KW24Cr 2180 KW25 Mn1519 KW26Fe 1811 KW27 Co 1768 KCu28 Ni 1728 KCu29Cu 1357 KCu30 Zn 692 KMg31Ga 302 Kα-Ga32 Ge 1211 Kd-C33As 1090 Kb-P34Se 494 Kγ-Se35Br 265 KCl36 Kr 115 KCu37 Rb 312 KW38 Sr 1050 KW39 Y 1799 KW40Zr 2128 KW41Nb 2750 KW42 Mo 2896 KW43 Tc 2430 KMg44 Ru 2607 KMg45 Rh 2237 KCu46 Pd 1828 KCu47 Ag 1234 KCu48 Cd 594 KMg49 In 429 KIn50 Sn 505 Kβ-Sn51 Sb 903 Kα-As52Te 722 Kγ-Se53I 386 KCl54 Xe 161 KCu55 Cs301 KW56 Ba1000 KW 71Lu1925 KMg72 Hf 2506 KW73 Ta 3290 KW74 W 3695 KW75 Re 3459 KMg76 Os 3306 KMg77 Ir2719 KCu78 Pt 2041 KCu79 Au 1337 KCu80 Hg 234 Kα-Hg81 Tl 557 KW82 Pb 600 KCu83 Bi 544 Kα-As84 Po 527 Kβ-Po85 At 575 K??86 Rn 202 K?87Fr281 K??88 Ra973 KW 103Lr1900 K??104 Rf?105 Db?106 Sg?107 Bh?108 Hs?109 Mt?110 Ds?111 Rg?112 Cn?113 Nh?114 Fl?115 Mc?116 Lv?117 Ts?118 Og? colspan="3" 57La1193 KW 58Ce1068 KW 59Pr1208 KW 60Nd 1297 KW 61Pm1315 KW 62Sm1345 KW 63Eu1099 KW 64Gd1585 KW 65Tb1629 KW 66Dy1680 KW 67Ho1734 KMg 68Er1802 KMg 69Tm1818 KMg 70Yb1097 KW colspan="3" 89Ac1323 KCu 90Th2115 KW 91Pa1841 KW 92U1405 KW 93Np917 KW 94Pu912 KW 95Am1449 KW 96Cm1613 KCu 97Bk1259 KCu 98Cf1173 KCu 99Es1133 KCu100Fm1800 K??101Md 1100 K??102No 1100 K?? Legend:

Predicted structures The following table give predictions for the crystalline structure of elements 85–87, 100–113 and 118; all but radon have not been produced in bulk. Most probably Cn and Fl would be liquids at STP (ignoring radioactive self-heating concerns). Calculations have difficulty replicating the experimentally known structures of the stable alkali metals, and the same problem affects Fr; nonetheless, it is probably isostructural to its lighter congeners. The latest predictions for Fl could not distinguish between FCC and HCP structures, which were predicted to be close in energy. No predictions are available for elements 115–117.

Predicted crystal structures of highly unstable elements1H2He3 Li4 Be5 B6 C7 N8 O9 F10 Ne11 Na12 Mg13 Al 14 Si 15 P 16 S 17 Cl 18 Ar 19K20 Ca 21Sc22Ti 23 V24Cr 25 Mn26Fe 27 Co 28 Ni 29Cu 30 Zn 31Ga 32 Ge 33As 34Se 35Br 36 Kr 37 Rb 38 Sr 39 Y 40Zr 41Nb 42 Mo 43 Tc 44 Ru 45 Rh 46 Pd 47 Ag 48 Cd 49 In 50 Sn 51 Sb 52Te 53I 54 Xe 55 Cs56 Ba 71Lu72 Hf 73 Ta 74 W 75 Re 76 Os 77 Ir78 Pt 79 Au 80 Hg 81 Tl 82 Pb 83 Bi 84 Po 85 At [Cu]86 Rn [Cu]87Fr[W]88 Ra 103Lr[Mg]104 Rf[Mg]105 Db[W]106 Sg[W]107 Bh[Mg]108 Hs[Mg]109 Mt[Cu]110 Ds[W]111 Rg[W]112 Cn[Mg]113 Nh[Mg]114 Fl 115 Mc 116 Lv 117 Ts 118 Og[Cu] colspan="3" 57La 58Ce 59Pr 60Nd 61Pm 62Sm 63Eu 64Gd 65Tb 66Dy 67Ho 68Er 69Tm 70Yb colspan="3" 89Ac 90Th 91Pa 92U 93Np 94Pu 95Am 96Cm 97Bk 98Cf 99Es100Fm [Cu]101Md [Cu]102No [Cu] Legend: [...] predicted structure

Structure types The following is a list of structure types which appear in the tables above. Regarding the number of atoms in the unit cell, structures in the rhombohedral lattice system have a rhombohedral primitive cell and have trigonal point symmetry but are also often also described in terms of an equivalent but nonprimitive hexagonal unit cell with three times the volume and three times the number of atoms.

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° Lemire, R. J. et al., 2001URL 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 Lemire, R.J. et al.,Chemical Thermodynamics of Neptunium and Plutonium, Elsevier, Amsterdam, 2001URL 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.Harry L. Yakel, A REVIEW OF X-RAY DIFFRACTION STUDIES IN URANIUM ALLOYS. The Physical Metallurgy of Uranium Alloys Conference, Vail, Colorado, Feb. 1974 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 . 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 . 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 Rm(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 Rm(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 Rm(No. 166) 3 (rh.)9 (hex.) 12 nearest neighbours complex hcp with 9-layer repeat: ABCBCACAB....A.F Wells (1962) Structural Inorganic Chemistry 3d Edition Oxford University Press α-Hg A10 Rhombohedral Rm(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 Rm(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 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 In the real dhcp structures of 5 lanthanides (including β-Ce) 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).Nevill Gonalez Swacki & Teresa Swacka, Basic elements of Crystallography, Pan Standford Publishing Pte. Ltd., 2010 β-N (none) Hexagonal P63/mmc(No. 194) 4 α-Po Ah Cubic Pmm(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 Pmn(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 I3m(No. 217) 58 Unit cell contains Mn atoms in 4 different environments. Distorted bcc W A2 Cubic Imm(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 Fmm(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 Fdm(No. 227) 8 The diamond cubic (DC) structure. Specifically the diamond form of Carbon.

Close packed metal structures

The observed crystal structures of many metals can be described as a nearly mathematical close-packing of equal spheres. A simple model for both of these is to assume that the metal atoms are spherical and are packed together as closely as possible. 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. The following types can be viewed as a regular buildup of close-packed layers: Mg type (hexagonal close packing) has alternate layers positioned directly above/below each other: A,B,A,B,...