 |
| General |
| Name | Selenium |
| Symbol | Se |
| Number | 34 |
| Group Number | 16 |
| Group | Non-Metal, Chalcogen |
| Block | p |
| Density | 4.79 g/cm3 |
| Atomic Weight | 78.96 g/mol |
| Atomic Volume | 16.45 cm3/mol |
| Discover | 1818 |
|
| States |
| State | Solid |
| Melting Point | 494 K |
| Boiling Point | 958 K |
| Triple Point | Nil |
| Critical Point | 1766 K |
| Heat of Fusion | 6.69 kJ/mol |
| Heat of Vaporization | 95.48 kJ/mol |
|
| Energies |
| First Ionization Energy | 940.9 kJ/mole |
| Second Ionization Energy | 2044.5 kJ/mole |
| Third Ionization Energy | 2973.7 kJ/mole |
| Electronegativity | 2.55 |
| Electron Affinity | 194.97 kJ/mole |
| Specific Heat | 0.32 J/gK |
| Heat Atomization | 227 kJ/mole atoms |
|
| Oxidation and Electrons |
| Shells | 2,8,18,6 |
| Electron Configuration | [Ar] 3d10 4s2 4p4 |
| Minimum Oxidation Number | -2 |
| Maximum Oxidation Number | 6 |
| Minimum Common Oxidation Number | -2 |
| Maximum Common Oxidation Number | 6 |
|
| Appearance and Characteristics |
| Crystal Structure | hexagonal |
| Characteristics | 6 forms |
| Color | black |
| Uses | Xerography, medicines |
| Hardness | 2 mohs |
| Toxicity | Yes |
|
| Reactions |
| Reaction with Air | vigorous, w/ht =>SeO2 |
| Reaction with 6M HCl | None |
| Reaction with 15M HNO3 | mild, =>H2SeO3, NOx |
| Reaction with 6M NaOH | None |
|
| Other Forms |
| Number of Isotopes | 6 |
| Hydride | SeH2 |
| Oxide | SeO2 SeO3 |
| Chloride | Se2Cl2 Se4Cl16 |
|
| Radius |
| Atomic Radius | 119 pm |
| Ionic Radius (1+ ion) | Nil |
| Ionic Radius (1- ion) | Nil |
| Ionic Radius (2+ ion) | Nil |
| Ionic Radius (2- ion) | 184 pm |
| Ionic Radius (3+ ion) | Nil |
|
| Conductivity |
| Thermal Conductivity | 0.52 J/m-sec-deg |
| Electrical Conductivity | 0 1/mohm-cm |
| Polarizability | 3.8 A3 |
|
| Abundance |
| Source | Cu smelting by-product |
| Relation Abundance Solar System | 1.793 log |
| Abundance Earth's Crust | -1.3 log |
|
