Input interpretation
red selenium | element types
Result
selenium
Periodic table location
Periodic table location
Image
Image
Basic elemental properties
atomic symbol | Se atomic number | 34 short electronic configuration | [Ar]4s^23d^104p^4 Aufbau diagram | 4p 3d 4s block | p group | 16 period | 4 atomic mass | 78.971 u (unified atomic mass units)
Thermodynamic properties
phase at STP | solid | melting point | gray selenium | 217 °C boiling point | gray selenium | 684.9 °C critical temperature | gray selenium | 1766 K critical pressure | gray selenium | 27.2 MPa molar heat of fusion | gray selenium | 6.69 kJ/mol molar heat of vaporization | gray selenium | 95.48 kJ/mol specific heat at STP | 321.2 J/(kg K) (rank: 37th) | (properties at standard conditions)
Material properties
density | black selenium | 4.28 g/cm^3 | red selenium | 4.39 g/cm^3 | gray selenium | 4.81 g/cm^3 liquid density | 3.99 g/cm^3 | molar volume | 16.39 cm^3/mol | Mohs hardness | 2 (≈ gypsum) | Brinell hardness | 736 MPa (rank: 20th) | bulk modulus | 8.3 GPa (rank: 60th) | shear modulus | 3.7 GPa | Young's modulus | 10 GPa (rank: 57th) | Poisson ratio | 0.33 (rank: 15th) | refractive index | 1.000895 | sound speed | 3350 m/s (rank: 29th) | thermal conductivity | 0.52 W/(m K) (rank: 79th) | (properties at standard conditions)
Electromagnetic properties
magnetic type | diamagnetic | volume magnetic susceptibility | -1.93×10^-5 | mass magnetic susceptibility | -4×10^-9 m^3/kg (cubic meters per kilogram) | molar magnetic susceptibility | -3.16×10^-10 m^3/mol (cubic meters per mole) | work function | 5.9 eV (Polycrystalline) | threshold frequency | 1.427×10^15 Hz (hertz) | color | (gray) | refractive index | gray selenium | 1.000895
Reactivity
valence | 6 electronegativity | 2.55 electron affinity | 195 kJ/mol (kilojoules per mole) first ionization energy | 941 kJ/mol (kilojoules per mole) ionization energies | 941 kJ/mol | 2045 kJ/mol | 2973.7 kJ/mol | 4144 kJ/mol | 6590 kJ/mol | 7880 kJ/mol | 14990 kJ/mol
Reactivity
Atomic properties
term symbol | ^3P_2 atomic radius | 115 pm covalent radius | 120 pm van der Waals radius | 190 pm (electronic ground state properties)
(neutral selenium atomic spectrum)
Abundances
universe abundance | 3×10^-6 mass% (rank: 32nd) meteorite abundance | 0.0013 mass% (rank: 25th) crust abundance | 5×10^-6 mass% (rank: 69th) ocean abundance | 4.5×10^-8 mass% (rank: 35th) human abundance | 5×10^-6 mass% (rank: 33rd) universe molar abundance | 5×10^-8 mol% (rank: 33rd) meteorite molar abundance | 2.9×10^-4 mol% (rank: 27th) ocean molar abundance | 3.5×10^-9 mol% (rank: 46th) crust molar abundance | 9.9×10^-7 mol% (rank: 70th) human molar abundance | 4×10^-7 mol% (rank: 32nd)
Nuclear properties
half-life | (stable) stable isotopes | Se-80 (49.61%) | Se-78 (23.77%) | Se-76 (9.37%) | Se-77 (7.63%) | Se-74 (0.89%) nuclear spin | Se-65: 3/2^- | Se-66: 0^+ | Se-67: 5/2^- | Se-68: 0^+ | Se-70: 0^+ | Se-71: 5/2^- | Se-72: 0^+ | Se-73: 9/2^+ | Se-74: 0^+ | Se-75: 5/2^+ | Se-76: 0^+ | Se-77: 1/2^- | Se-78: 0^+ | Se-79: 7/2^+ | Se-80: 0^+ | Se-81: 1/2^- | Se-82: 0^+ | Se-83: 9/2^+ | Se-84: 0^+ | Se-85: 5/2^+ | Se-86: 0^+ | Se-87: 5/2^+ | Se-88: 0^+ | Se-89: 5/2^+ | Se-90: 0^+ | Se-91: 1/2^+ | Se-92: 0^+ | Se-93: 1/2^+ | Se-94: 0^+ unstable isotopes | Se-79 (0.295 Myr) | Se-75 (119.79 days) | Se-72 (8.4 days) | Se-73 (7.14 h) | Se-70 (41.17 min) | Se-83 (22.33 min) | Se-81 (18.45 min) | Se-71 (4.73 min) | Se-84 (186 s) | Se-68 (35.5 s) | Se-85 (31.7 s) | Se-69 (27.4 s) | Se-86 (15.3 s) | Se-87 (5.5 s) | Se-88 (1.53 s) | Se-89 (410 ms) | Se-91 (270 ms) | Se-67 (136 ms) | Se-65 (50 ms) | Se-66 (33 ms) | Se-92 (300 ns) | Se-90 (300 ns) | Se-94 (150 ns) | Se-93 (150 ns) neutron cross-section | 11.7 b neutron mass absorption | 0.0056 m^2/kg
Identifiers
CAS number | 7782-49-2