|
34
Se
78.96
Selenium |
Appearance & Characteristics | Reactions |
Other Forms Radius | Conductivity | Abundance
General:
| Name: Selenium | Symbol: Se |
| Group: Non-Metal, Chalcogen | Atomic weight: 78.96 |
| Density @ 293 K: 4.79 g/cm3 | Atomic volume: 16.45 cm3/mol |
| Group: Non-Metal, Chalcogen | Discovered: 1818 |
States
| State (s, l, g): solid | |
| Melting point: 490.2 K | Boiling point: 958 K |
| Heat of fusion: 6.694 kJ/mol | Heat of vaporization: 37.70 kJ/mol |
Energies
| 1st ionization energy: 940.9 kJ/mole | |
| Electronegativity: 2.55 | 2nd ionization energy: 2044.5 kJ/mole |
| Electron affinity: 194.97 kJ/mole | 3rd ionization energy: 2973.7 kJ/mole |
| Specific heat: 0.32 J/gK | Heat atomization: 227 kJ/mole atoms |
Oxidation & Electrons
| Shells: 2,8,18,6 | Electron configuration: [Ar] 3d10 4s2 4p4 |
| Minimum oxidation number: -2 | Maximum oxidation number: 6 |
| Min. common oxidation no.: -2 | Max. common oxidation no.: 6 |
Appearance & Characteristics
| Structure: parallel chains | Color: black |
| Uses: Xerography, medicines | Toxicity: yes |
| Hardness: 2 mohs | Characteristics: 6 forms |
Reactions
| Reaction with air: vigorous, w/ht => SeO2 | |
| Reaction with 6 M HCl: none | Reaction with 6 M HCl: none |
| Reaction with 15 M HNO3: mild, => H2SeO3, NOx | Reaction with 6 M NaOH: |
Other Forms
| Number of isotopes: 6 | Hydride(s): SeH2 |
| Oxide(s): SeO2 SeO3 | Chloride(s): Se2Cl2 Se4Cl16 |
Radius
| Ionic radius (2- ion): 184 pm | Ionic radius (1- ion): pm |
| Atomic radius: 119 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): pm | Ionic radius (3+ ion): pm |
Conductivity
| Thermal conductivity: 0.52 J/m-sec-deg | |
| Electrical conductivity: 0 1/mohm-cm | Polarizability: 3.8 A^3 |
Abundance
| Source: Cu smelting by-product | |
| Rel. abund. solar system: 1.793 log | Abundance earth's crust: -1.3 log |
| cost, pure: 14 $/100g | cost, bulk: $/100g |
