This periodic table colors the 86 elements from hydrogen to radon by the crystal structure that is stable at 25 °C and 1 atm. Besides the color, each cell shows a letter code (B = body-centered cubic, F = face-centered cubic, H = hexagonal close-packed, D = diamond structure, O = other, G = gas, L = liquid). Switch the view to melting point, density or Young’s modulus to see the values as six shades. Tap a cell or pick an element below to see its lattice parameters (with c and c/a for HCP), the measured density and the density calculated from the lattice parameter, the melting point, the metallic radius and the allotropic transformations. For BCC, FCC and diamond-structure elements, a link opens the XRD calculator with that structure and lattice parameter. The default is iron (BCC).
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Periodic table
Selected element
Lattice parameters and transformation temperatures are from the table of crystal structures of the elements in the ASM Alloy Phase Diagram Database (values at 25 °C and 1 atm; Zn and Tc from WebElements). Densities and melting points are CRC Handbook values; for K, V, Mn, Tc, Ru and Ta, whose CRC density differs by 1.5% or more from the value calculated from the lattice parameter, and for Ce, where the room-temperature phase was chosen, the density is from Wolfram ElementData. The melting points of S, Ga, Kr and Xe are WebElements values. Young’s moduli are WebElements values for polycrystals (CRC Handbook for the rare earths and a few others; Zr and Hf, whose values differ widely between sources, are left blank), and metallic radii are values converted to 12-fold coordination (WebElements). Rows marked “calculated” are computed on this page from the lattice parameters and the standard atomic weights (CIAAW). Transformation temperatures can differ by a few to several tens of degrees between sources (422–450 °C for Co, 700–727 °C for β-Mn). Values that could not be confirmed are shown as “—”.
See it as a graph
Other inputs stay at their current values while the chosen input varies from 1/4 to 4 times its current value. The red dot is the current value.
Reading the colors and letter codes
In the crystal structure view, each element is colored by the structure of the phase that is stable at 25 °C and 1 atm, and a letter code is written in the cell. B is body-centered cubic (BCC), F is face-centered cubic (FCC), H is hexagonal close-packed (HCP), D is the diamond structure, O is another structure, G is a gas and L is a liquid. Of the 86 elements, 14 are BCC, 13 are FCC, 22 are HCP, 2 have the diamond structure (Si and Ge), 21 have other structures, 11 are gases, 2 are liquids (Br and Hg) and 1 (At) has an unconfirmed structure. The table shows how elements in the same group tend to share a structure: the alkali metals of group 1 (Li to Cs) are all BCC, groups 5 (V, Nb, Ta) and 6 (Cr, Mo, W) are BCC, groups 10 (Ni, Pd, Pt) and 11 (Cu, Ag, Au) are FCC, and group 4 (Ti, Zr, Hf) is HCP. Some groups are mixed, however, such as group 8 with Fe (BCC) and Ru and Os (HCP).
Lattice parameter and density
For a cubic crystal, the density follows from the number of atoms per unit cell n, the atomic weight M, the Avogadro constant N_A and the lattice parameter a as ρ = nM/(N_A·a³). For BCC n = 2, for FCC n = 4 and for the diamond structure n = 8. For iron (BCC, a = 0.28665 nm), ρ = 2 × 55.845 g/mol ÷ (6.022 × 10²³ /mol × (0.28665 × 10⁻⁷ cm)³) ≈ 7.874 g/cm³, in good agreement with the measured 7.87 g/cm³. For HCP the cell volume is (√3/2)a²c with n = 2. The “density from lattice parameters” row shows this value, and for most elements it agrees with the measured density within 1%. Real samples differ slightly because of impurities, vacancies and the measurement temperature. For strontium, the CRC value of 2.64 g/cm³ and the calculated 2.58 g/cm³ differ by about 2%. Some sources (the element tables on Wikipedia) list the 2.58 g/cm³ derived from the lattice parameter as the density, so the sources themselves disagree.
Atomic radius and atomic packing factor
If atoms are treated as touching hard spheres, the radius is half the distance between nearest neighbors. In BCC the atoms touch along the cube diagonal, so r = √3a/4; in FCC they touch along the face diagonal, so r = √2a/4; in the diamond structure r = √3a/8. This gives 124.1 pm for iron and 127.8 pm for copper. The metallic radius shown separately is converted to a coordination number of 12, so for the BCC transition metals (V, Cr, Fe, Nb, Mo, Ta, W), with eight nearest neighbors, it is 1–3% larger than half the nearest-neighbor distance (126 pm versus 124.1 pm for iron). For the BCC alkali metals the listed value is about the same as, or slightly smaller than, half the nearest-neighbor distance. The atomic packing factor is the fraction of the cell volume filled by the spheres: 0.68 for BCC, 0.74 for FCC and ideal HCP, and 0.34 for the diamond structure. Among the HCP metals, zinc (c/a = 1.856) and cadmium (1.886) have c/a well above the ideal 1.633, so the hard-sphere packing factor drops to about 0.65.
Examples of allotropic transformations
Some elements change their crystal structure with temperature; this is called an allotropic transformation. Iron changes from BCC α-iron to FCC γ-iron at 912 °C and back to BCC δ-iron at 1394 °C. Titanium changes from the HCP α phase to the BCC β phase at 882 °C, and zirconium at 863 °C and hafnium at 1743 °C change from HCP to BCC in the same way. Cobalt is FCC above 422 °C. Below 13 °C, diamond-structure gray tin is more stable than body-centered tetragonal white tin, and the density drops with a volume increase of about 26%. For elements that are solid at 25 °C, the details panel lists the transformations at 1 atm given in the ASM table. Phases that appear only under pressure are not listed.
Reading the melting point, density and modulus views
The melting point, density and Young’s modulus views show the values in six shades and write the value in each cell. The bins are shown in the legend, and darker means larger. Melting points are highest in groups 5 to 8 of period 6 (Ta, W, Re, Os), with tungsten (3422 °C) the highest of all metals, while the alkali metals melt low and cesium (28.5 °C) and gallium (29.76 °C) melt below body temperature. Osmium (22.59 g/cm³) and iridium (22.5 g/cm³) have the highest densities, and lithium (0.534 g/cm³) has the lowest of the solids. Young’s modulus is largest for iridium (528 GPa), rhenium (463 GPa), ruthenium (447 GPa) and tungsten (411 GPa) (osmium is blank for lack of a confirmed value), and 10 GPa or less for the alkali metals. The moduli are polycrystalline values that vary with texture, purity and test method, and sources can differ by around 10%.
Conditions and sources of the values
Lattice parameters are the 25 °C, 1 atm values in the table of crystal structures of the elements in the ASM Alloy Phase Diagram Database. Because of thermal expansion, they become slightly larger at higher temperature. Densities and melting points are CRC Handbook values; each density was compared with the value calculated from the lattice parameter and atomic weight, and where they differed by 1.5% or more the Wolfram ElementData value was used. Young’s moduli are WebElements values (CRC Handbook for the rare earths and a few others); silicon is shown as the range over single-crystal directions, rhodium and promethium are left blank because their values could not be confirmed, and zirconium (68–99 GPa) and hafnium (78–141 GPa) because the values differ widely between sources. These are representative values for learning; use the original data or measurements for design and research.
The density is ρ = nM/(N_A a³), and the FCC unit cell contains n = 4 atoms. With a = 0.3615 nm = 3.615×10⁻⁸ cm, a³ ≈ 4.724×10⁻²³ cm³, so ρ = 4 × 63.55 / (6.022×10²³ × 4.724×10⁻²³) ≈ 8.94 g/cm³, in good agreement with the measured value of about 8.96 g/cm³. About 2.23 g/cm³ is calculated with n = 1 (treating it as SC), and about 4.47 g/cm³ with n = 2 (treating it as BCC). The conversion from nm to cm (1 nm = 10⁻⁷ cm) is also a common slip, so make the units consistent before cubing.
In BCC, atoms touch along the body diagonal, so √3a = 4r gives r = √3a/4 = 1.732 × 0.2866/4 ≈ 0.124 nm. About 0.101 nm comes from applying the FCC relation r = √2a/4, and about 0.143 nm from applying the simple cubic relation r = a/2. FCC γ-iron has a larger lattice parameter of about 0.36 nm, but its atomic radius differs by only a few percent; most of the difference in lattice parameter comes from the difference in atomic arrangement (structure).
The volume per atom is the unit-cell volume divided by the number of atoms in the cell. For BCC it is 0.2904³/2 ≈ 0.01225 nm³, and for FCC 0.3647³/4 ≈ 0.01213 nm³, so the change is about −0.97%: a contraction of about 1%. The volume decreases because the structure becomes the more densely packed FCC; calling it an expansion is a sign error. Doubling comes from comparing unit-cell volumes directly (0.3647³/0.2904³ ≈ 1.98), overlooking that the BCC cell holds 2 atoms and the FCC cell 4. This volume change can be observed as a transformation point in dilatometry.
FAQ
What do the letters B, F, H, D, O, G and L in the cells mean?
B is body-centered cubic (BCC), F is face-centered cubic (FCC), H is hexagonal close-packed (HCP), D is the diamond structure, O is another structure, G means a gas at 25 °C and L a liquid. Astatine (At) is marked “?” because no bulk sample exists and its structure has not been confirmed.
At what temperature are the lattice parameters given?
At 25 °C and 1 atm (from the ASM table; Zn and Tc from WebElements). They increase slightly with temperature because of thermal expansion. Some sources list values measured at low temperature; for example, one source (Wolfram ElementData) gives 0.5585 nm for rubidium, compared with 0.5705 nm at 25 °C on this page.
Which elements get a link to the XRD calculator?
Elements whose 25 °C structure is BCC, FCC, diamond or simple cubic (Po), plus carbon as metastable diamond. The calculator opens with the structure, the lattice parameter, the Cu Kα wavelength (0.15406 nm) and the first allowed reflection (110 for BCC, 111 for FCC and diamond, 100 for simple cubic), so you can check which peaks the extinction rules allow and where they appear. The XRD calculator handles only cubic crystals, so HCP and other elements have no link.
Why do the density and the density from lattice parameters differ?
The listed density is measured on real samples, while the calculated (X-ray) density assumes a perfect crystal. Impurities, vacancies and the measurement temperature make them differ slightly. For most elements the difference is within 1%, but for strontium it is about 2% (some sources list the 2.58 g/cm³ derived from the lattice parameter).
Why is Young’s modulus blank for some elements?
It is blank for gases and liquids, for elements without a reliable value in the sources, for rhodium, whose value is flagged as possibly wrong, for promethium, which has only an estimate, and for zirconium (68–99 GPa) and hafnium (78–141 GPa), whose values differ widely between sources. For silicon, the single-crystal modulus varies from 130 to 188 GPa with direction, so a range is shown and the cell is not shaded in the modulus view.
Isn’t cerium face-centered cubic?
The ASM table gives double hexagonal close-packed β-Ce at 25 °C, which becomes face-centered cubic γ-Ce above 61 °C. Both phases can occur near room temperature, and some textbooks list cerium as FCC at room temperature. This page follows the ASM table and uses the density of β-Ce (6.689 g/cm³); FCC γ-Ce has a density of 6.770 g/cm³ (CRC).