Selenium
Selenium is a chemical element with atomic number 34, with the chemical symbol Se. It is a nonmetal, chemically related to sulfur and tellurium, and rarely occurring in its elemental state in nature. It is toxic in large amounts, but trace amounts of it are necessary for cellular function in most, if not all, animals, forming the active center of the enzymes glutathione peroxidase and thioredoxin reductase (which indirectly reduce certain oxidized molecules in animals and some plants) and three known deiodinase enzymes (which convert one thyroid hormone to another). Selenium requirements in plants differ by species, with some plants apparently requiring none.
| General | |
|---|---|
| Atomic number: | 34 |
| Symbol: | Se |
| Atomic weight: | 78.96 |
| Boiling Point (C): | 685 |
| Melting Point (C): | 217 |
| Density: | 4.79 |
| heatVapor: | 3.34 |
| heatFusion: | 1.25 |
| Electrical Conductivity: | 0.08 |
| Thermal Conductivity: | 1e-05 |
| Specific Heat Capacity: | 0.084 |
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