34Se78.971
Selenium
Reactive non-metal · element 34 · group 16, period 4
Quick facts
| Symbol | Se |
|---|---|
| Atomic number | 34 |
| Relative atomic mass | 78.971 |
| Category | Reactive non-metal |
| Position | group 16, period 4 |
| State at 20 °C | Solid |
| Melting point | 221 °C |
| Boiling point | 685 °C |
| Density | 4.81 g/cm³ |
| Electronegativity | 2.55 |
| Electron configuration | [Ar] 3d10 4s2 4p4 |
About Selenium
Selenium has the symbol Se and atomic number 34, which means every selenium atom has 34 protons in its nucleus and, in a neutral atom, 34 electrons. At room temperature it is a solid.
Non-metals are usually poor conductors of heat and electricity. They form covalent bonds with other non-metals and negative ions with metals.
It melts at 221 °C and boils at 685 °C.
Explore it
See where selenium sits, and drag the temperature slider to watch it melt and boil, on the interactive periodic table. Practise with quizzes on OmniEx.