Selenium (Se)
Metalloid element, belongs to group 16 of the periodic table. Multiple allotropic forms exist. Chemically resembles sulphur. Discovered in 1817 by Jons J. Berzelius.
| Atomic Number | 34 |
|---|---|
| Atomic Weight | 78.971 |
| Mass Number | 80 |
| Group | 16 |
|---|---|
| Period | 4 |
| Block | p |
| Protons | 34 p+ |
|---|---|
| Neutrons | 46 n0 |
| Electrons | 34 e- |
Properties
| Atomic Radius | 115 pm
|
|---|---|
| Atomic Volume | 16.5 cm³/mol
|
| Covalent Radius | 115.99999999999999 pm
|
| Metallic Radius | 117 pm
|
| Ionic Radius | 198 pm
|
| Crystal Radius | 184 pm
|
| Van der Waals radius |
190 pm
|
| Density | 4.809 g/cm³
|
| Boiling Point | 958.1 K
|
| Melting Point | 490 K
|
| Electrons per shell | 2, 8, 18, 6 |
| Electronegativity |
2.55
|
| Electrophilicity | 2.240849270962 eV/particle
|
| Proton Affinity | |
| Electron Affinity | 2.02067 eV/particle
|
| Ionization Potential | 9.752392 eV/particle
|
| Heat of Vaporization | 59.7 kJ/mol
|
| Heat of Fusion | 5.23 kJ/mol
|
| Heat of Formation | 227.2 kJ/mol
|
| Molar Heat Capacity | 25.363 J/(mol K)
|
| Specific Heat Capacity | 0.321 J/(g⋅K)
|
| Thermal Conductivity | 0.52 W/(m K)
|
| Gas Basicity | |
| Dipole Polarizability | 28.9 a₀
|
| C6 Dispersion Coefficient | 210 a₀
|
| Oxidation States | -2, 2, 4, 6 |
| Color | Gray
|
| Crystal Structure | Simple Monoclinic (HEX) |
| Lattice Constant | 4.36 Å
|
| Bulk Modulus | |
| Electrical Resistivity | |
| Electron Configuration | [Ar] 3d10 4s2 4p4 |
| Magnetic Ordering | |
| Magnetic Susceptibility | |
| Phase | Solid |
| Poisson Ratio | |
| Shear Modulus | |
| Young's Modulus | |
| Allotropes | |
| Alternate Names | |
| Adiabatic Index | |
| Appearance | |
| Electric Conductivity | |
| Critical Pressure | |
| Critical Temperature | |
| Curie Point | |
| Electrical | |
| Hardness | |
| Magnetic Susceptibility | |
| Magnetic | |
| Neel Point | |
| Neutron Cross Section | |
| Neutron Mass Absorption | |
| Gas Phase | |
| Quantum Numbers | |
| Refractive Index | |
| Space Group | |
| Speed of Sound | |
| Superconducting Point | |
| Thermal Expansion | |
| Valence Electrons | |
| Classification | |
| Category | Other nonmetals, Nonmetals |
| CAS Group | VIB |
| IUPAC Group | VIA |
| Glawe Number | 95 |
| Mendeleev Number | 101 |
| Pettifor Number | 93 |
| Geochemical Class | semi-volatile |
| Goldschmidt Class | chalcophile |
| Radioactivity | |
| Radioactive | No |
| Decay Mode | |
| Half-Life | |
| Lifetime | |
| Abundance | |
| Abundance in Earth's crust | 0.05 mg/kg
|
| Abundance in Oceans | 0.0002 mg/L
|
| Abundance in Human Body | |
| Abundance in Meteor | |
| Abundance in Sun | |
| Abundance in Universe | 3×10-6% |
Isotopes of Selenium
Stable Isotopes
74Se 76Se 77Se 78Se 80Se 82Se
Unstable Isotopes
65Se 66Se 67Se 68Se 69Se 70Se 71Se 72Se 73Se 75Se 79Se 81Se 83Se 84Se 85Se 86Se 87Se 88Se 89Se 90Se 91Se 92Se 93Se 94Se
History
Selenium was first observed in about the year 1300 by the alchemist Arnold of Villanova. Selenium was discovered in 1817 by Jöns Jacob Berzelius and Johan Gottlieb Gahn who noted the similarity of the new element to the previously-known tellurium. In 1873, Willoughby Smith found that the electrical resistance of grey selenium was dependent on the ambient light. From the Greek word Selene, moon
| Discoverers | Jöns Berzelius |
|---|---|
| Discovery Location | Sweden |
| Discovery Year | 1818 |
| Name Origin | Greek: selênê (moon). |
Many of selenium's compounds, such as selenates and selenites, are highly toxic
Selenium deficiency in animals can lead to slow growth
Uses
Selenium is used in the glass industry to decolorize glass and to make red-colored glasses and enamels. It is used as a catalyst in many chemical reactions. It is also used as a photographic toner, and as an additive to stainless steel. Selenium sulfide is used in anti-dandruff shampoos. Light causes it to conduct electricity more easily. It is used in photoelectric cells, TV cameras, xerography machines and as a semiconductor in solar batteries and rectifiers. Also colors glass red.
Sources
Obtained from lead, copper and nickel refining. Conducts electricity when struck by light.